JP5226537B2 - Information recording medium, method for manufacturing the same, sputtering target, and film forming apparatus - Google Patents

Description

  The present invention relates to an information recording medium that records and reproduces information by irradiation with a laser beam or application of electric energy, and a sputtering target and a film forming apparatus used for manufacturing the information recording medium.

  Conventionally, as an information recording medium, there is a phase change information recording medium in which a recording layer is formed of a phase change material. Among the phase change information recording media, one in which information is optically recorded, erased, rewritten and reproduced using a laser beam is called an optical phase change information recording medium (hereinafter referred to as an optical recording medium). Information is recorded on the optical recording medium by changing the state of the phase change material between, for example, a crystalline phase and an amorphous phase by heat generated by laser beam irradiation. Information is reproduced by detecting a difference in reflectance between the crystalline phase and the amorphous phase.

  Among rewritable optical recording media capable of erasing and rewriting information among optical recording media, the initial state of the recording layer is generally a crystalline phase. In the case of recording information, the recording layer is melted by irradiating a high-power laser beam, and then rapidly cooled to make the laser irradiation portion an amorphous phase. On the other hand, in the case of erasing information, the recording layer is heated by irradiating a laser beam having a power lower than that at the time of recording, and then slowly cooled to change the laser irradiation portion into a crystalline phase. To do. Also, by irradiating the recording layer with a laser beam that has been power-modulated with high power and low power, new information can be recorded while erasing the recorded information, that is, rewriting is possible.

  In order to perform erasing or rewriting at high speed, it is necessary to change the amorphous phase to the crystalline phase in a short time. That is, in the rewritable optical recording medium, in order to realize high erasing performance, it is necessary to form the recording layer with a phase change recording material having a high crystallization speed.

  Such a rewritable optical recording medium has a configuration in which a dielectric layer, a reflective layer, an interface layer, and the like are appropriately provided on the substrate in addition to the recording layer. The dielectric layer can be provided for the purpose of preventing evaporation of the recording layer and thermal deformation of the substrate during repeated recording, and efficiently causing light absorption and optical change of the recording layer by the optical interference effect. The dielectric layer is disposed on both sides of the recording layer. The reflective layer is provided for the purpose of efficiently using the irradiated laser beam and for improving the cooling rate and making the recording layer easily in an amorphous phase. The reflective layer is usually disposed behind the recording layer as seen from the laser beam irradiation side so that the reflective layer and the recording layer sandwich the dielectric layer. The interface layer is disposed between the recording layer and the dielectric layer as necessary, and is provided for the purpose of preventing interdiffusion of atoms and molecules between the recording layer and the dielectric layer.

Examples of known phase change materials include GeTe—Sb ₂ Te ₃ , GeTe—Bi ₂ Te ₃ , GeTe—SnTe, and the like. In particular, GeTe-Bi ₂ Te ₃ has a high crystallization speed. Therefore, when a recording layer of a rewritable optical recording medium is formed using this, excellent erasing performance can be obtained (see Patent Document 1).

  In order to increase the capacity of a rewritable optical recording medium, a method of providing two information layers on one optical recording medium has been reported (see Patent Document 2). Information can be recorded on each of the two information layers by a laser beam incident from one side of the medium. The same applies to reproduction. Therefore, the recording capacity of the optical recording medium having two information layers can be almost double the recording capacity of the optical recording medium having only one information layer.

  In this rewritable optical recording medium having two information layers, recording and reproduction of an information layer (hereinafter also referred to as a first information layer) far from the incident side is performed on an information layer on the incident side (hereinafter also referred to as a second information layer). ). Therefore, it is preferable that the second information layer has as high a transmittance as possible. Since the phase change material generally has a large extinction coefficient, the thickness of the recording layer of the second information layer is preferably thin in order to increase the transmittance of the recording layer.

  In order to increase the number of information layers for increasing the capacity, for example, to realize an optical recording medium having three or four information layers, an information layer on the incident side (third information layer or fourth information layer) is used. The transmittance of the layer) must be further increased, and the thickness of the recording layer needs to be further reduced.

JP-A 63-225935 JP 2000-36130 A

However, in the conventional GeTe-Bi ₂ Te ₃ recording layer, there is a problem that when the thickness is reduced in order to increase the transmittance, the crystallization speed is lowered and the erasing performance is greatly lowered. On the other hand, when the proportion of Bi ₂ Te ₃ is increased in the GeTe-Bi ₂ Te ₃ recording layer, the crystallization speed is increased and the erasing performance is improved, but the amorphous phase becomes unstable, and the signal reliability is increased. There was also the problem of a drop.

  The present invention solves the above-mentioned problems, an information recording medium having an excellent recording layer having a high crystallization speed and a stable amorphous phase, a method for producing the same, and such a recording layer It is an object of the present invention to provide a sputtering target and a film forming apparatus used for forming the film.

In order to achieve the above object, the present invention is an information recording medium including an information layer including a recording layer capable of causing a phase change, wherein the recording layer includes Sb and S, and the following formula (1): :
Sb _x S _100-x (Atom%) (1)
(Subscript x represents a composition ratio expressed in atomic%, and satisfies 50 ≦ x ≦ 98)
The information recording medium containing the material represented by these is provided.

Further, the present invention provides an information recording method including the step of forming an information layer including a step of forming a recording layer containing Sb and S by sputtering, which can cause a phase change, as a method for manufacturing the information recording medium of the present invention. In the method for manufacturing a medium, in the recording layer forming step, a sputtering target including Sb and S is used, and a film formed using the sputtering target is represented by the following formula (1):
Sb _x S _100-x (Atom%) (1)
(Subscript x represents a composition ratio expressed in atomic%, and satisfies 50 ≦ x ≦ 98)
The manufacturing method containing the material represented by these is provided.

The present invention also includes Sb and S as sputtering targets suitable for use in forming the recording layer of the information recording medium of the present invention, and the following formula (11):
Sb _X S _100-X (Atom%) (11)
(Subscript X represents a composition ratio expressed in atomic% and satisfies 50 ≦ X ≦ 98)
A sputtering target comprising a material represented by:

  The present invention further includes a power source, a vacuum vessel having an exhaust port and a gas supply port, a vacuum pump connected to the vacuum vessel via the exhaust port, an anode and a cathode disposed in the vacuum vessel, and the anode A film forming apparatus including a sputtering target connected to the film, wherein the sputtering target is the sputtering target of the present invention.

  The information recording medium of the present invention is a medium that exhibits a high erasure rate, excellent recording and reproduction characteristics, and high signal reliability. Moreover, the information recording medium manufacturing method of the present invention makes it possible to easily manufacture the information recording medium of the present invention. Furthermore, according to the sputtering target and the film forming apparatus of the present invention, the information recording medium of the present invention can be easily manufactured.

Sectional drawing of one structural example of the information recording medium of this invention Sectional drawing of one structural example of the information recording medium of this invention Sectional drawing of one structural example of the information recording medium of this invention Sectional drawing of one structural example of the information recording medium of this invention Sectional drawing of one structural example of the information recording medium of this invention Sectional drawing of one structural example of the information recording medium of this invention Sectional drawing of one structural example of the information recording medium of this invention Sectional drawing of one structural example of the information recording medium of this invention Sectional drawing of one structural example of the information recording medium of this invention Schematic of an example of a recording / reproducing apparatus for an information recording medium of the present invention Schematic of an example of a recording pulse waveform used for recording / reproducing of the information recording medium of the present invention The figure which shows typically a part of structure of the information recording medium of this invention, and an electrical information recording / reproducing apparatus. The figure which shows typically a part of structure of the high capacity | capacitance electrical information recording medium of this invention. The figure which shows typically a part of structure of the electrical information recording medium of this invention, and its recording / reproducing system. The figure which shows an example of the recording / erasing pulse waveform applied to the electrical information recording medium of this invention The figure which shows typically a part of film-forming apparatus which manufactures the information recording medium of this invention

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiment is an example, and the present invention is not limited to the following embodiment. Moreover, in the following embodiment, the same code | symbol may be attached | subjected to the same element and the overlapping description may be abbreviate | omitted.

(Embodiment 1)
As Embodiment 1, an example of the information recording medium of the present invention (hereinafter sometimes referred to as “recording medium” or “medium”) will be described. A partial cross-sectional view of the information recording medium 11 of Embodiment 1 is shown in FIG. The information recording medium 11 is an optical recording medium, and information is recorded and reproduced by collecting and irradiating the laser beam 31 with an objective lens 32.

  The information recording medium 11 has a configuration in which an information layer 40 and a transparent layer 23 are provided in this order on a substrate 21. The transparent layer 23 has a thickness smaller than that of the substrate 21. In the illustrated form, the laser beam is incident from the transparent layer 23 side.

  The shorter the wavelength λ of the laser beam 31, the smaller the spot diameter can be focused by the objective lens 32. However, if the wavelength λ is too short, the light absorption of the laser beam 31 by the transparent layer 23 or the like increases. Therefore, the wavelength λ of the laser beam is preferably in the range of 350 nm to 450 nm.

  As shown in FIG. 1, in the information layer 40, a reflective layer 402, a first dielectric layer 404, a recording layer 406, and a second dielectric layer 408 are provided in this order from the side closer to the substrate 21. . If necessary, as shown in FIG. 2, a reflective layer-side interface layer 403 is provided between the reflective layer 402 and the first dielectric layer 404, and between the first dielectric layer 404 and the recording layer 406. As the first interface layer 405, a second interface layer 407 may be provided between the second dielectric layer 408 and the recording layer 406.

  Information recording on the information recording medium 11 is performed by condensing the laser beam 31 from the transparent layer 23 side with the objective lens 32 and irradiating the recording layer 406 of the information layer 40. The information recorded on the information recording medium 11 is also performed by irradiating a laser beam in the same manner.

  The substrate 21 has a disk shape, is used to hold the information layer 40 and the transparent layer 23, and functions as a support when these layers are formed. A guide groove for guiding the laser beam 31 may be formed on the surface of the substrate 21 in contact with the information layer 40. The surface of the substrate 21 that does not contact the information layer 40 is preferably smooth. The substrate 21 can be formed using a polycarbonate resin, a polymethyl methacrylate resin, a polyolefin resin, a norbornene resin, glass, or a combination of these as a material. In particular, a polycarbonate resin is preferable as a material for the substrate 21 because it is excellent in transferability and mass productivity and is low in cost.

Next, each layer constituting the information layer 40 will be described.
The material of the recording layer 406 is a material that causes a phase change between a crystalline phase and an amorphous phase when irradiated with the laser beam 31. In the present invention, a material containing Sb and S is used as the material of the recording layer 406. If the recording layer 406 is composed of only Sb, the amorphous phase becomes unstable and the reliability of the signal is lowered. The amorphous phase can be stabilized by adding S to Sb. Further, by adding S to Sb, the transmittance of the recording layer 406 can be increased.

Specifically, when the recording layer 406 has a thickness of 7 nm, the crystallization temperature is Tx (when the phase change material 406 in an amorphous phase is gradually heated at 50 ° C./min at room temperature, the phase change occurs. When the recording layer 406 is made of only Sb, Tx = 100 ° C., whereas the recording layer 406 has Sb ₈₀ S ₂₀ (subscript is expressed in atomic%). Composition ratio), Tx = 200 ° C., and the amorphous phase is more stable than the recording layer made of only Sb.

Further, in the combination of Sb and S, when Sb is less than 50 atomic%, the crystallization speed is too low and erasing performance practical as a rewritable optical recording medium cannot be obtained. Therefore, in the recording layer 406, Sb and S are expressed by the following formula (1):
Sb _x S _100-x (Atom%) (1)
(Subscript x represents a composition ratio expressed in atomic%, and satisfies 50 ≦ x ≦ 98)
It is preferable that it is contained as a material represented by. When x exceeds 98, the effect of adding S to Sb cannot be obtained. More preferably, x satisfies 60 ≦ x ≦ 80. This formula shows the composition ratio when the number of Sb atoms and the number of S atoms are combined to be 100 atomic%. Therefore, the recording layer 406 may contain elements other than Sb and S.

  The recording layer preferably consists essentially of Sb atoms and S atoms. Here, the term “substantially” is used in consideration of unavoidably including a small amount of other elements (for example, elements contained in the atmospheric gas during sputtering). More specifically, when the ratio of atoms other than Sb and S is less than 10 atomic% among all atoms constituting the recording layer, it can be said that the recording layer is substantially composed of Sb and S. The ratio of atoms other than Sb and S is more preferably less than 1 atomic%.

  As a material for the recording layer 406, a material containing Sb and S and at least one element (M) selected from Ge, Sn, Bi, In, and Mn can be used. This is because the crystallization speed and the stability of the amorphous phase can be adjusted by adding the element represented by M to the material containing Sb and S described above. . For example, when Sn or Bi is added to a material composed of Sb and S, the crystallization speed of the material is increased. In addition, when In, Ge, and Mn are added to a material composed of Sb and S, respectively, the amorphous phase of the material can be stabilized.

Depending on the type of M, the preferred addition amount varies. Here, it is preferable to divide the five elements so that Ge, In, and Sn belong to the group M1, and Bi and Mn belong to the group M2. When the recording layer 406 includes M1, the recording layer 406 has the following formula (2):
(Sb _z S _1-z ) _100-y M1 _y (atomic%) (2)
(The subscript z represents the ratio of each atom when the total number of Sb atoms and the number of S atoms is 1, satisfying 0.5 ≦ z ≦ 0.98, and the subscript y is atomic%. Represents the composition ratio shown and satisfies 0 <y ≦ 30)
It is preferable that the material represented by these is included.

  In the above formula (2), M1 is at least one element selected from Ge, In, and Sn. As M1, two elements (for example, Ge and Sn, or In and Sn) may be included, and three elements may be included. z and y preferably satisfy 0.5 ≦ z ≦ 0.98 and 2 ≦ y ≦ 20, and more preferably satisfy 0.6 ≦ z ≦ 0.8 and 5 ≦ y ≦ 20.

  When the recording layer 406 includes the material of the above formula (2), the recording layer more preferably substantially consists of Sb atoms, S atoms, and M1 atoms. Here, the term “substantially” is used in consideration of unavoidably including a small amount of other elements (for example, elements contained in the atmospheric gas during sputtering). More specifically, when the ratio of atoms other than Sb, S, and M1 is less than 10 atomic% among all atoms constituting the recording layer, the recording layer is substantially composed of Sb, S, and M1. It can be said that The ratio of atoms other than Sb, S and M1 is more preferably less than 1 atomic%.

When the recording layer 406 includes M2, the recording layer 406 has the following formula (3):
(Sb _a S _1-a ) _100-b M2 _b (atomic%) (3)
(The subscript a represents the ratio of each atom when the number of Sb atoms and the number of S atoms are combined, and satisfies 0.5 ≦ a ≦ 0.98, and the subscript b is atomic%. Represents the composition ratio shown and satisfies 0 <b ≦ 20)
It is preferable that the material represented by these is included. In the above formula, M2 is at least one element selected from Bi and Mn. M2 may include both Bi and Mn. More preferably, b satisfies 2 ≦ b ≦ 10.

  When the recording layer 406 includes the material of the above formula (3), the recording layer preferably consists essentially of Sb atoms, S atoms, and M2 atoms. Here, the term “substantially” is used in consideration of unavoidably including a small amount of other elements (for example, elements contained in the atmospheric gas during sputtering). More specifically, when the ratio of atoms other than Sb, S, and M2 is less than 10 atomic% among all atoms constituting the recording layer, the recording layer is substantially composed of Sb, S, and M2. It can be said that The proportion of atoms other than Sb, S and M2 is more preferably less than 1 atomic%.

Alternatively, the recording layer 406 includes both M1 and M2, and the following formula (4):
(Sb _c S _1-c ) _100-de M1 _d M2 _e (atomic%) (4)
(The subscript c represents the ratio of each atom when the total number of Sb atoms and the number of S atoms is 1, satisfying 0.5 ≦ c ≦ 0.98, and the subscripts d and e are atoms % Represents the composition ratio and satisfies 0 <d <30, 0 <e ≦ 20, 0 <d + e ≦ 30)
It may contain the material represented by these.

  When the recording layer 406 includes the material of the above formula (4), the recording layer preferably consists essentially of Sb atoms, S atoms, M1 atoms, and M2 atoms. Here, the term “substantially” is used in consideration of unavoidably including a small amount of other elements (for example, elements contained in the atmospheric gas during sputtering). More specifically, when the ratio of atoms other than Sb, S, M1, and M2 is less than 10 atomic% among all atoms constituting the recording layer, the recording layer has Sb, S, M1, and M2. It can be said that it consists essentially of The ratio of atoms other than Sb, S, M1, and M2 is more preferably less than 1 atomic%.

  The recording layer 406 preferably has an amorphous phase that can be easily changed to a crystalline phase when irradiated with a laser beam, and preferably does not change to a crystalline phase when the laser beam is not irradiated. If the thickness of the recording layer 406 is too small, sufficient reflectivity and reflectivity change cannot be obtained. On the other hand, if the thickness of the recording layer 406 is too large, the heat capacity increases and the recording sensitivity decreases. Therefore, the thickness of the recording layer 406 is preferably in the range of 5 nm to 15 nm, and more preferably in the range of 8 nm to 12 nm.

  The reflective layer 402 has an optical function of increasing the amount of light absorbed by the recording layer 406 and a thermal function of diffusing heat generated in the recording layer 406. As the material of the reflective layer 402, a material containing at least one element selected from Ag, Au, Cu, and Al can be used. For example, an alloy such as Ag—Cu, Ag—Ga—Cu, Ag—Pd—Cu, Ag—Nd—Au, AlNi, AlCr, Au—Cr, or Ag—In can be used as the material of the reflective layer 402. . In particular, an Ag alloy is preferable as a material for the reflective layer 402 because of its high thermal conductivity. The greater the thickness of the reflective layer 402, the stronger the thermal diffusion function. However, if the thickness of the reflective layer 402 is too large, heat is diffused excessively, and the recording sensitivity of the recording layer 406 decreases. Therefore, the thickness of the reflective layer 402 is preferably in the range of 30 nm to 200 nm, and more preferably in the range of 70 nm to 140 nm.

The first dielectric layer 404 is located between the recording layer 406 and the reflective layer 402, and adjusts the thermal function for adjusting the thermal diffusion from the recording layer 406 to the reflective layer 402, and the reflectance and absorption rate. It has an optical function. Examples of the material of the first dielectric layer 404 include ZrO ₂ , HfO ₂ , ZnO, SiO ₂ , SnO ₂ , Cr ₂ O ₃ , TiO ₂ , In ₂ O ₃ , Ga ₂ O ₃ , and Y ₂ O _3. One compound selected from oxides such as CeO ₂ , CeO ₂ , and DyO ₂ , sulfides such as ZnS and CdS, and carbides such as SiC, or a mixture of two or more compounds selected from these compounds For example, ZrO ₂ —SiO ₂ , ZrO ₂ —SiO ₂ —Cr ₂ O ₃ , ZrO ₂ —SiO ₂ —Ga ₂ O ₃ , HfO ₂ —SiO ₂ —Cr ₂ O ₃ , ZrO ₂ —SiO ₂ —In ₂ O _3, ZnS-SiO _2, and SnO ₂ -SiC can be used. In particular, ZnS—SiO ₂ is excellent as a material for the first dielectric layer. ZnS—SiO ₂ has a high film formation rate, is transparent, and has good mechanical properties and moisture resistance.

  If the thickness of the first dielectric layer 404 is too large, the cooling effect of the reflective layer 402 will be weakened, and thermal diffusion from the recording layer 406 will be reduced, making it difficult for the recording layer to become amorphous. On the other hand, if the thickness of the first dielectric layer 404 is too small, the cooling effect of the reflective layer 402 becomes strong, the thermal diffusion from the recording layer 406 increases, and the sensitivity decreases. Therefore, the thickness of the first dielectric layer 404 is preferably in the range of 2 nm to 40 nm, and more preferably in the range of 8 nm to 30 nm.

The reflective layer side interface layer 403 functions to prevent the reflective layer 402 from being corroded or destroyed by the material of the first dielectric layer 404. Specifically, when the reflective layer 402 includes Ag and the first dielectric layer 404 includes S (for example, ZnS—SiO ₂ is included), the reflective layer-side interface layer 403 reacts with Ag and S. The resulting corrosion of the reflective layer 402 is prevented.

As a material of the reflective layer side interface layer 403, a metal other than Ag, for example, Al or an Al alloy can be used. Further, as the material of the reflective layer side interface layer 403, a dielectric material not containing S can be used. Such materials are, for _{example, ZrO 2, HfO 2, ZnO} , SiO 2, SnO 2, Cr 2 O 3, TiO 2, In 2 O 3, Ga 2 O 3, Y 2 O 3, CeO 2, and DyO One compound selected from oxides such as ₂ and carbides such as SiC, or a mixture of two or more compounds selected from these compounds, such as ZrO ₂ —SiO ₂ , ZrO ₂ —SiO ₂ —Cr ₂ O ₂ , ZrO ₂ —SiO ₂ —Ga ₂ O ₂ , HfO ₂ —SiO ₂ —Cr ₂ O ₃ , ZrO ₂ —SiO ₂ —In ₂ O ₃ , and SnO ₂ —SiC. Alternatively, the reflective layer side interface layer 403 may be formed using C or the like.

  If the thickness of the reflective layer side interface layer 403 is too large, the thermal and optical functions of the first dielectric layer 404 are hindered. If the thickness is too small, corrosion and destruction of the reflective layer 402 are sufficiently prevented. It may not be done. Therefore, the thickness of the reflective layer side interface layer 403 is preferably in the range of 1 nm to 100 nm, and more preferably in the range of 5 nm to 40 nm.

The first interface layer 405 has a function of preventing mass transfer that occurs between the first dielectric layer 404 and the recording layer 406 by repeated recording. The first interface layer 405 is preferably formed of a material having a high melting point that does not melt during recording and good adhesion to the recording layer 406. The material of the first interface layer 405 is, for example, ZrO ₂ , HfO ₂ , ZnO, SiO ₂ , SnO ₂ , Cr ₂ O ₃ , TiO ₂ , In ₂ O ₃ , Ga ₂ O ₃ , Y ₂ O ₃ , CeO. ₂ and oxides such as DyO ₂ , sulfides such as ZnS and CdS, and carbides such as SiC, or a mixture of two or more compounds selected from these compounds, such as ZrO ₂ — _{SiO 2, ZrO 2 -SiO 2 -Cr} 2 O 3, ZrO 2 -SiO 2 -Ga 2 O 3, HfO 2 -SiO 3 -Cr 2 O 3, ZrO 2 -SiO 2 -In 2 O 3, ZnS-SiO ₂ , SnO ₂ —SiC can be used. Or C. In particular, Ga ₂ O ₃ , ZnO, In ₂ O _{3 and the} like are preferable as the material of the first interface layer 405. These are because the adhesiveness with the recording layer 406 is good.

  When the thickness of the first interface layer 405 is too small, the effect as the interface layer is not exhibited, and when it is too large, the thermal and optical functions of the first dielectric layer 404 are hindered. Therefore, the thickness of the first interface layer 405 is preferably in the range of 0.3 nm to 15 nm, and more preferably in the range of 1 nm to 8 nm.

The second dielectric layer 408 exists at a position closer to the laser beam incident side than the recording layer 406. The second dielectric layer 408 has a function of preventing corrosion and deformation of the recording layer 406 and an optical function of adjusting reflectance and absorption rate. An example of the material of the second dielectric layer 408 is the same as the example given as the material of the first dielectric layer 404. In particular, ZnS—SiO ₂ is excellent as a material for the second dielectric layer. ZnS—SiO ₂ has a high film formation rate, is transparent, and has good mechanical properties and moisture resistance.

  If the thickness of the second dielectric layer 408 is too large, the function of preventing the recording layer 406 from being corroded and deformed is deteriorated. Further, the thickness of the second dielectric layer 408 satisfies the condition that the amount of reflected light changes greatly when the recording layer 406 is in the crystalline phase and in the amorphous phase by calculation based on the matrix method. So that it can be determined strictly. The thickness of the second dielectric layer 408 is preferably in the range of 20 nm to 80 nm.

  Similar to the first interface layer 405, the second interface layer 407 has a function of preventing mass transfer that occurs between the second dielectric layer 408 and the recording layer 406 due to repeated recording. Therefore, the second interface layer 407 is preferably formed using the material exemplified as the material of the first interface layer 405 so as to have the same performance as the first interface layer 405.

  Similar to the first interface layer 405, the thickness of the second interface layer 407 is preferably in the range of 0.3 nm to 15 nm, and more preferably in the range of 1 nm to 8 nm.

  The reflective layer 402, the first dielectric layer 404, the recording layer 406, and the second dielectric layer 408 are provided, and the reflective layer side interface layer 403, the first interface layer 405, and the second dielectric layer 408 are provided as necessary. The information layer 40 is configured by providing the interface layer 407.

  The transparent layer 23 is on the incident side of the information layer 40 with the laser beam 31 and protects the information layer 40. The transparent layer 23 preferably has a small light absorption with respect to the laser beam 31. The transparent layer 23 is made of polycarbonate resin, polymethyl methacrylate resin, polyolefin resin, norbornene resin, ultraviolet curable resin (for example, acrylic resin and epoxy resin), slow-acting thermosetting resin, glass, or a combination thereof. And the like can be used. Further, a sheet made of these materials may be used as the transparent layer 23.

  If the thickness of the transparent layer 23 is too small, the function of protecting the information layer 40 is not exhibited. If the thickness of the transparent layer 23 is too large, the distance from the incident side of the laser beam 31 to the information layer 40 in the information recording medium 11 is longer than the focal length of the objective lens 32, and the focus of the laser beam 31 is increased. The recording layer 406 cannot be matched. When NA is 0.85, the thickness of the transparent layer is preferably in the range of 5 μm to 150 μm, and more preferably in the range of 40 μm to 110 μm.

The information recording medium 11 can be manufactured by the method described below.
First, the information layer 40 is formed on the substrate 21 (thickness is, for example, 1.1 mm). The information layer 40 is formed of a multilayer film, and each layer (film) can be formed by sequentially sputtering. Note that, depending on the material constituting the substrate 21, the substrate 21 may exhibit high hygroscopicity. Therefore, if necessary, a substrate annealing step for removing moisture may be performed before sputtering.

  Each layer is made of a sputtering target of a material constituting each layer, in a rare gas atmosphere such as Ar gas, Kr gas, or Xe gas, or a rare gas and a reactive gas (at least one gas selected from oxygen gas and nitrogen gas). It can be formed by sputtering in a mixed gas atmosphere. As the sputtering method, a DC (direct current) sputtering method and an RF (high frequency) sputtering method are properly used as necessary. Usually, DC sputtering is preferably used because it can be performed at a high film formation rate. However, a material having low conductivity such as a dielectric material may not be sputtered by a DC sputtering method, and in that case, an RF sputtering method is used. A highly conductive dielectric material, a dielectric material whose conductivity is improved by preparing a sputtering target, and the like can be sputtered by a DC sputtering method or a pulsed DC sputtering method.

  The composition of each layer formed by sputtering may not completely match the composition of the original sputtering target. For example, in the case of an oxide, oxygen deficiency is likely to occur by sputtering. In that case, oxygen vacancies can be compensated by using oxygen gas as the reaction gas. The composition of the sputtering target is determined so that the film formed by sputtering has a desired composition. The composition of the sputtering target may coincide with the composition of the film formed by sputtering.

  Here, an example of a sputtering apparatus (film forming apparatus) used for manufacturing the information recording medium of the present invention will be described. FIG. 16 schematically shows how a film is formed using a sputtering apparatus. As shown in FIG. 16, in this sputtering apparatus, a vacuum pump (not shown) is connected to the vacuum vessel 667 via the exhaust port 668, and a high vacuum is maintained in the vacuum vessel 667. A gas with a constant flow rate is supplied from the gas supply port 669. A substrate 671 (here, the substrate is a base material on which a film is deposited) is placed on the anode 670. By grounding the vacuum vessel 667, the vacuum vessel 667 and the substrate 671 are kept at the anode.

  The sputtering target 672 is connected to the cathode 673 and is connected to a power source 674 via a switch (not shown). In the illustrated form, the cathode 673 is water cooled. By applying a predetermined voltage between the anode 670 and the cathode 673, particles are emitted from the sputtering target 672, and a thin film is formed on the substrate 671. This apparatus can be used to form each layer that forms the information layer, and can also be used to manufacture other forms of media described below.

  In the illustrated form, the formation of the information layer 40 specifically starts with the formation of the reflective layer 402 on the substrate 21. The reflective layer 402 can be formed by DC sputtering a sputtering target made of a metal or an alloy constituting the reflective layer 402 in a rare gas atmosphere or a mixed gas atmosphere of a rare gas and a reactive gas.

  Subsequently, a reflective layer side interface layer 403 is formed on the reflective layer 402 as necessary. The reflective layer side interface layer 403 is formed by sputtering a sputtering target made of the material constituting the reflective layer side interface layer 403 in a rare gas atmosphere or a mixed gas atmosphere of a rare gas and a reactive gas. When the material of the reflective layer side interface layer 403 is a highly conductive material such as a metal, a DC sputtering method is used. When the material is a low conductivity material such as an oxide, an RF sputtering method is preferably used.

  Subsequently, a first dielectric layer 404 is formed on the reflective layer side interface layer 403 or the reflective layer 402. The first dielectric layer 404 is formed by sputtering a sputtering target made of the material constituting the first dielectric layer 404 in an rare gas atmosphere or a mixed gas atmosphere of a rare gas and a reactive gas by an RF sputtering method. By forming. In some cases, the first dielectric layer 404 may be formed by DC sputtering.

  Subsequently, a first interface layer 405 is formed on the first dielectric layer 404 as necessary. The first interface layer 405 is formed by RF sputtering a sputtering target made of a material constituting the first interface layer 405 in a rare gas atmosphere or a mixed gas atmosphere of a rare gas and a reactive gas. In some cases, the first interface layer 405 may be formed by a DC sputtering method.

Subsequently, the recording layer 406 is formed on the first interface layer 405 or on the first dielectric layer 404. The recording layer 406 may be formed, for example, by sputtering a sputtering target containing Sb and S in a rare gas atmosphere. Specifically, the recording layer 406 can be formed by DC sputtering a sputtering target whose composition is adjusted so that the recording layer 406 has a composition including the material represented by the above formula (1). Such a sputtering target includes, for example, Sb and S, and the following formula (11):
Sb _X S _100-X (Atom%) (11)
(Subscript X represents a composition ratio expressed in atomic% and satisfies 50 ≦ X ≦ 98)
It is a sputtering target containing the material represented by these.

  Further, as a sputtering target used to form the recording layer 406, a sputtering target obtained by adding at least one element selected from Sn, Bi, In, Ge, and Mn to the above sputtering target may be used. Specifically, recording is performed by DC sputtering of a sputtering target whose composition is adjusted so that the recording layer 406 has a composition including the material represented by the above formula (2), (3), or (4). Layer 406 can be formed. Such a sputtering target contains the material represented by following formula (12)-(14), for example.

_{(Sb Z S 1-Z)} 100-Y M1 Y ( atomic%) (12)
(M1 is at least one element selected from Ge, In and Sn, and the subscript Z represents the ratio of each atom when the total number of Sb atoms and S atoms is 1, ≦ Z ≦ 0.98 is satisfied, and the subscript Y represents a composition ratio represented by atomic%, and 0 <Y ≦ 30 is satisfied)

(Sb _A S _1-A ) _100-B M2 _B (Atom%) (13)
(M2 is at least one element selected from Bi and Mn, and the subscript A represents the ratio of each atom when the total number of Sb atoms and the number of S atoms is 1, and 0.5 ≦ A ≦ 0.98 is satisfied, and the subscript B represents the composition ratio expressed in atomic%, and 0 <B ≦ 20 is satisfied)

(Sb _C S _1-C ) _100-DE M1 _D M2 _E (atomic%) (14)
(M1 is at least one element selected from Ge, In and Sn, M2 is at least one element selected from Bi and Mn, and the subscript C is the sum of the number of Sb atoms and the number of S atoms. 1 represents the ratio of each atom, 0.5 ≦ C ≦ 0.98 is satisfied, and the subscripts D and E represent the composition ratio represented by atomic%, and 0 <D <30, 0 <E ≦ 20, 0 <D + E ≦ 30)

  Alternatively, the recording layer 406 includes Sb, S, M (where M is at least one element of Sn, Bi, In, Ge, and Mn), Sb—S, Sb—M, S—M, and Sb—S—. It can also be formed by simultaneously sputtering at least two sputtering targets selected from sputtering targets represented by M. In that case, since the composition of the recording layer to be obtained is determined according to the number of sputtering targets to be used and the output of the power source, they are appropriately selected and the formed film has a desired composition. Sputtering is performed as follows. The use of two or more sputtering targets in this way is useful when it is difficult to form a mixture sputtering target.

  Subsequently, a second interface layer 407 is formed on the recording layer 406 as necessary. The second interface layer 407 is formed by RF sputtering a sputtering target made of a material constituting the second interface layer 407 in a rare gas atmosphere or a mixed gas atmosphere of a rare gas and a reactive gas. In some cases, the second interface layer 407 may be formed by DC sputtering.

  Subsequently, a second dielectric 408 is formed on the second interface layer 407 or the recording layer 406. The second dielectric layer 408 is formed by RF sputtering a sputtering target made of the material constituting the second dielectric layer 408 in a rare gas atmosphere or a mixed gas atmosphere of a rare gas and a reactive gas. To do. In some cases, the second dielectric layer 407 may be formed by DC sputtering.

  In this way, the information layer 40 is formed on the substrate 21, and then the transparent layer 23 is formed on the information layer 40. The transparent layer 23 is formed by applying an ultraviolet curable resin (for example, acrylic resin and epoxy resin) or a slow-acting thermosetting resin on the second information layer 41 by spin coating, and then curing the resin. Can be formed. The transparent layer 23 may be formed using a disk-shaped plate or sheet made of polycarbonate resin, polymethyl methacrylate resin, polyolefin resin, norbornene resin, glass, or the like. In this case, the transparent layer 23 is formed by applying an ultraviolet curable resin or a slow-acting thermosetting resin on the information layer 40, adhering a plate or sheet to the applied resin, and then curing the curable resin. Can be formed. Alternatively, an adhesive resin can be applied uniformly to the plate or sheet in advance, and then the plate or sheet is brought into close contact with the second dielectric layer 408.

  The recording layer 406 of the information recording medium 11 is normally in an amorphous state in a state where the film is formed (as-depo state). Therefore, an initialization process for crystallizing the recording layer 406 may be performed by irradiating a laser beam, if necessary.

  The information recording medium 11 is manufactured as described above. In the present embodiment, a sputtering method is used as a method for forming each layer constituting the information layer. The formation method is not limited to this, and a vacuum deposition method, an ion plating method, an MBE (Molecular Beam Epitaxy) method, or the like can also be used.

(Embodiment 2)
As Embodiment 2, another example of the information recording medium of the present invention will be described. FIG. 3 shows a partial cross-sectional view of the information recording medium 12 of the second embodiment. The information recording medium 12 is a multilayer optical recording medium, and information is recorded and reproduced by condensing and irradiating the laser beam 31 with an objective lens 32.

  In the information recording medium 12, N information layers (N is N are N information layer 41, first information layer 41, second information layer 42... N−1 information layer 48, Nth information layer 49). ≧ 2) and a transparent layer 23 are provided in this order (hereinafter, the Kth (1 ≦ K ≦ N) information layer counted from the side opposite to the laser incident side is referred to as a Kth information layer). . Separation layers 22,..., 28, 29 are provided between the information layers.

  In the information recording medium 12, the laser beam reaching the information layer closer to the substrate 21 than the Nth information layer 49 and the reflected light are transmitted through the information layer closer to the incident side of the laser beam 31 than the information layer. Attenuates. Therefore, the first information layer 41, the second information layer 42,..., And the N-1th information layer 48 need to have high recording sensitivity and high reflectance, and the second information layer 42. The −1 information layer 48 and the Nth information layer 49 need to have high transmittance.

  Since the materials, shapes, and functions of the substrate 21 and the transparent layer 23 are as described in the first embodiment, detailed descriptions thereof are omitted here.

  The separation layers 22,..., 28, and 29 are layers provided to distinguish the focus positions of the first information layer 41, the second information layer 42, and the Nth information layer 49 of the information recording medium 12. is there. The thicknesses of the separation layers 22,..., 28, 29 are preferably equal to or greater than the focal depth determined by the numerical aperture NA of the objective lens 32 and the wavelength λ of the laser beam 31. On the other hand, all the information layers separated by the separation layers 22,..., 28, 29 need to be within a range where light can be collected by the objective lens 32. In order to satisfy this requirement, it is necessary to make the separation layers 22,. If λ is 405 nm and NA is 0.85, the thickness of the separation layers 22,..., 28, 29 is preferably in the range of 5 μm to 50 μm.

  The separation layers 22,..., 28, 29 preferably have small light absorption with respect to the laser beam 31. Guide grooves for guiding the laser beam 31 may be formed on the laser beam 31 irradiation side of the separation layers 22,. The material of the separation layers 22,..., 28, 29 is polycarbonate resin, polymethyl methacrylate resin, polyolefin resin, norbornene resin, ultraviolet curable resin, slow-acting thermosetting resin, glass, or a combination thereof. It may be a thing.

  When the present invention is provided as a medium having a multilayer structure, such as the medium shown in FIG. 3, at least one K-th information layer (N is an integer of 1 ≦ K ≦ N) out of N information layers. Any recording layer that can cause a phase change may be used. For example, only the Nth information layer 49 includes Sb and S described above in relation to the recording layer 406 of Embodiment 1, and is represented by any one of the above formulas (1) to (4). It may be a rewritable information layer including a recording layer containing a material (in this specification including the following description, such a recording layer may be referred to as a “recording layer containing Sb and S”). In this case, the (N−1) information layers from the first information layer 41 to the (N−1) th information layer 48 may be read-only information layers or write-once information layers that can be written only once.

  Alternatively, at least one of the N-1 information layers from the Nth information layer to the second information layer may be a rewritable information layer including a recording layer containing Sb and S. Since the materials represented by the above formulas (1) to (4) including Sb and S have high transparency, the information layers other than the first information layer (that is, the light passing through the information layer is different information). It is suitable for constituting a recording layer of an information layer used for recording / reproducing the layer. Alternatively, all the information layers may have a recording layer containing Sb and S. When only one recording layer including Sb and S is provided in the medium, the recording layer including Sb and S is preferably included in the Nth information layer. This is because the Nth information layer requires the highest transmittance.

Hereinafter, the configuration of the Nth information layer 49 will be described.
As shown in FIG. 3, in the Nth information layer 49, the transmittance adjusting layer 491, the reflective layer 492, the first dielectric layer 494, the recording layer 496, and the second dielectric layer 498 are arranged from the side close to the substrate 21. Are provided in this order. Further, if necessary, a reflective layer side interface layer is provided between the reflective layer 492 and the first dielectric layer 494, and a first interface layer is provided between the first dielectric layer 494 and the recording layer 496. A second interface layer may be provided between the second dielectric layer 498 and the recording layer 496. In FIG. 3, the reflective layer side interface layer can be shown as a layer represented by 493 between the layers 491 and 492, and the first interface layer is 495 between the layers 492 and 494. The second interface layer can be shown as a layer represented by 497 between layers 496 and 498.

As a material for the recording layer 496, a material similar to the material for the recording layer 406 in Embodiment 1 can be used. A material containing Sb and S is particularly suitable as a material for the recording layer 496 because of its high transparency. When the other information layer has a recording layer containing Sb and S, the material of the recording layer 496 is (Ge—Sn) Te, GeTe—Sb ₂ Te ₃ , (Ge—Sn) Te—Sb. ₂ Te ₃ , GeTe—Bi ₂ Te ₃ , (Ge—Sn) Te—Bi ₂ Te ₃ , GeTe— (Sb—Bi) ₂ Te ₃ , (Ge—Sn) Te— (Sb—Bi) ₂ Te ₃ , _{GeTe- (Bi-In) 2 Te} 3, (Ge-Sn) Te- (Bi-In) 2 Te 3, Sb-Te, Sb-Ge, (Gb-Te) -Ge, Sb-In, (Sb- A material containing any of (Te) -In, Sb-Ga, and (Sb-Te) -Ga can also be used. The thickness of the recording layer 496 is preferably 10 nm or less and more preferably in the range of 2 nm to 8 nm in order to increase the transmittance of the Nth information layer 49.

  The reflective layer 492 has a function similar to that of the reflective layer 402 in Embodiment 1. That is, it has an optical function of increasing the amount of light absorbed by the recording layer 496 and a thermal function of diffusing heat generated in the recording layer 496. Therefore, an example of the material of the reflective layer 492 is the same as the example of the material of the reflective layer 402 described in Embodiment 1. In particular, an Ag alloy is preferable as a material for the reflective layer 492 because of its high thermal conductivity.

  In order to increase the transmittance of the Nth information layer 49, the thickness of the reflective layer 492 is preferably 20 nm or less, and more preferably in the range of 3 nm to 14 nm. When the thickness of the reflective layer 492 is within this range, the optical and thermal functions of the reflective layer 492 are sufficiently exhibited.

  The first dielectric layer 494 has a function similar to that of the first dielectric layer 404 of the first embodiment. That is, it has a thermal function for adjusting thermal diffusion from the recording layer 496 to the reflective layer 492 and an optical function for adjusting reflectivity, absorptivity, and the like. Therefore, an example of the material of the first dielectric layer 494 is the same as the example of the material of the first dielectric layer 404 of the first embodiment.

  The thickness of the first dielectric layer 494 is preferably in the range of 1 nm to 40 nm, and preferably in the range of 4 nm to 30 nm, so that the optical and thermal functions are sufficiently exhibited. More preferred.

  The second dielectric layer 498 has a function similar to that of the second dielectric layer 408 of the first embodiment. That is, it has a function of preventing corrosion and deformation of the recording layer 496 and an optical function of adjusting reflectivity, absorption rate, and the like. Therefore, an example of the material of the second dielectric layer 498 is the same as the example of the material of the second dielectric layer 408 described in Embodiment 1. The thickness of the second dielectric layer 498 satisfies the condition that the amount of reflected light changes greatly when the recording layer 496 is in the crystalline phase and in the amorphous phase by calculation based on the matrix method. Can be determined strictly.

  The transmittance adjusting layer 491 is made of a dielectric and has a function of adjusting the transmittance of the Nth information layer 49. By this transmittance adjustment layer 491, the transmittance Tc (%) of the Nth information layer 49 when the recording layer 496 is in a crystalline phase and the Nth information layer 49 when the recording layer 496 is in an amorphous phase. Both the transmittance Ta (%) can be increased.

The transmittance adjustment layer 491 includes TiO ₂ , ZrO ₂ , HfO ₂ , ZnO, Nb ₂ O ₅ , Ta ₂ O ₅ , Al ₂ O ₃ , SiO ₂ , Cr ₂ O ₃ , CeO ₂ , Ga ₂ O ₃ , and One kind selected from oxides such as Bi ₂ O ₃ , nitrides such as Ti—N, Zr—N, Nb—N, Ge—N, Cr—N, and Al—N, and sulfides such as ZnS Or a mixture of two or more compounds selected from these compounds. The refractive index n _t and the extinction coefficient k _t of the transmittance adjusting layer 491 are preferably n _t ≧ 2.4 and kt ≦ 0.1 in order to increase the transmittances Tc and Ta. As a material satisfying this condition, it is preferable to use TiO ₂ or a material containing TiO ₂ . Since these materials have a large refractive index (n _t = 2.6 to 2.8) and a small extinction coefficient (k _t = 0.0 to 0.1), the transmittance formed using these materials The adjustment layer 491 is due to effectively increasing the transmittance of the Nth information layer 49.

The thickness of the transmittance adjusting layer 491 is approximately λ / 8n t _(However, lambda is the wavelength lambda of the laser beam 31, n _t is the refractive index of the material of the transmittance adjustment layer 491) when it is, the transmittance Tc and Ta is increased more effectively. If λ = 405 nm and n _t = 2.6, the thickness of the transmittance adjustment layer 491 is preferably in the range of 5 nm to 36 nm in consideration of other characteristics such as reflectance. .

  The reflective layer side interface layer, the first interface layer, and the second interface layer have functions similar to those of the reflective layer side interface layer 403, the first interface layer 405, and the second interface layer 407 of Embodiment 1, respectively. Have. Therefore, examples of the material of these layers are the same as the materials of the reflective layer side interface layer 403, the first interface layer 405, and the second interface layer 407 described in Embodiment 1, respectively.

The information recording medium 12 can be manufactured by the method described below.
First, N−1 information layers from the first information layer 41 to the N−1th information layer 48 are sequentially stacked on the substrate 21 via the separation layers 22,. Each information layer is formed of a multilayer film, and each layer (film) constituting the information layer can be formed by sequentially sputtering. In addition, the separation layers 22,..., 28, etc. are coated with UV curable resin (for example, acrylic resin and epoxy resin) or slow-acting thermosetting resin on the information layer, and then rotated entirely. Thus, the resin can be uniformly extended (spin coating), and then the resin can be cured. When the separation layers 22,..., 28, etc. are provided with a guide groove for the laser beam 31, the guide groove causes the substrate (mold) on which the groove is formed to adhere to the resin before curing, and the resin is cured in that state. After that, the guide groove can be formed by peeling off the substrate (mold).

  In this way, after the N−1 information layers are stacked on the substrate 21 via the separation layers 22,..., 28, etc., the separation layer 29 is formed on the N−1th information layer. .

Subsequently, an Nth information layer 49 is formed on the separation layer 29.
Specifically, first, the transmittance adjustment layer 491 is formed on the separation layer 29. The transmittance adjusting layer 491 is formed by sputtering a sputtering target made of a material constituting the transmittance adjusting layer 491 in a rare gas atmosphere or a mixed gas atmosphere of a rare gas and a reactive gas by an RF sputtering method or a DC sputtering method. Can be formed.

  Subsequently, a reflective layer 492 is formed on the transmittance adjustment layer 491. The reflective layer 492 can be formed by a method similar to the method for forming the reflective layer 402 in Embodiment 1.

  Subsequently, a reflective layer side interface layer is formed on the reflective layer 492 as necessary. The reflective layer side interface layer can be formed by a method similar to the method of forming the reflective layer side interface layer 403 of the first embodiment.

  Subsequently, a first dielectric layer 494 is formed on the reflective layer side interface layer or on the reflective layer 492. The first dielectric layer 494 can be formed by a method similar to the method for forming the first dielectric layer 404 of the first embodiment.

  Subsequently, a first interface layer is formed on the first dielectric layer 494 as necessary. The first interface layer can be formed by a method similar to the method for forming the first interface layer 405 of Embodiment 1.

  Subsequently, a recording layer 496 is formed on the first interface layer or on the first dielectric layer 494. In the case where Sb and S are included, the recording layer 496 can be formed by a method similar to the method for forming the recording layer 406 of Embodiment 1. In the case where the recording layer 406 is formed of another material, a sputtering target may be selected according to the material and formed by a sputtering method.

  Subsequently, a second interface layer is formed on the recording layer 496 as necessary. The second interface layer can be formed by a method similar to the method for forming the second interface layer 407 in Embodiment 1.

  Subsequently, a second dielectric 498 is formed on the second interface layer or the recording layer 496. The second dielectric layer 498 can be formed by a method similar to the method for forming the second dielectric layer 408 of Embodiment 1.

  In this way, the Nth information layer 49 is formed on the separation layer 29, and then the transparent layer 23 is formed on the Nth information layer 49. The transparent layer 23 can be formed by the method described in the first embodiment.

  Since each recording layer of the information recording medium 12 is normally in an amorphous state as it is formed, an initialization process for crystallizing the recording layer by irradiating a laser beam as necessary is performed. You may go.

  The information recording medium 12 can be manufactured as described above. In the present embodiment, a sputtering method is used as a method for forming each layer constituting the information layer. The formation method is not limited to this, and a vacuum deposition method, an ion plating method, an MBE method, or the like can also be used.

(Embodiment 3)
As a third embodiment, an example of a recording medium in which N is 2 in the multilayer recording medium of the present invention of the second embodiment, that is, constituted by two information layers will be described. FIG. 4 shows a partial cross-sectional view of the information recording medium 13 according to the third embodiment. The information recording medium 13 is a two-layer optical recording medium, and information is recorded and reproduced by condensing and irradiating the laser beam 31 with an objective lens 32.

  In the information recording medium 13, the first information layer 41, the separation layer 22, the second information layer 42, and the transparent layer 23 are provided in this order on the substrate 21.

  The materials, shapes, and functions of the substrate 21, the separation layer 22, and the transparent layer 23 are as described in the first and second embodiments.

  The second information layer 42 plays the same role as the Nth information layer 49 described in the second embodiment (since N = 2 in the third embodiment). Therefore, each layer constituting the second information layer 42 can be formed of the material of each layer constituting the Nth information layer 49 described in the second embodiment. The shape and function of each layer constituting the second information layer 42 are the same as the shape and function of each layer constituting the Nth information layer 49 described in the second embodiment.

Hereinafter, the configuration of the first information layer 41 will be described.
As shown in FIG. 4, in the first information layer 41, a reflective layer 412, a first dielectric layer 414, a recording layer 416, and a second dielectric layer 418 are provided in this order from the side close to the substrate 21. Yes. Further, if necessary, a reflective layer side interface layer is provided between the reflective layer 412 and the first dielectric layer 414, and a first interface layer is provided between the first dielectric layer 414 and the recording layer 416. A second interface layer may be provided between the second dielectric layer 418 and the recording layer 416. In FIG. 4, the reflective layer side interface layer can be shown as a layer represented by 413 between the layers 412 and 414, and the first interface layer can be represented by 415 between the layers 414 and 416. The second interface layer can be shown as a layer represented by 417 between layers 416 and 418.

As the material of the recording layer 416, the same material as the material of the recording layer 406 of Embodiment 1 can be used. When the second information layer 42 has a recording layer containing Sb and S, the material of the recording layer 416 is (Ge—Sn) Te, GeTe—Sb ₂ Te ₃ , (Ge—Sn) Te. _{-Sb 2 Te 3, GeTe-Bi} 2 Te 3, (Ge-Sn) Te-Bi 2 Te 3, GeTe- (Sb-Bi) 2 Te 3, (Ge-Sn) Te- (Sb-Bi) 2 Te _{3, GeTe- (Bi-In)} 2 Te 3, (Ge-Sn) Te- (Bi-In) 2 Te 3, Sb-Te, Sb-Ge, (Gb-Te) -Ge, Sb-In, ( It may be Sb-Te) -In, Sb-Ga or (Sb-Te) -Ga.

  The reflective layer 412, the first dielectric layer 414, and the second dielectric layer 418 have the same functions as the reflective layer 402, the first dielectric layer 404, and the second dielectric layer 408 of Embodiment 1, respectively. And can be formed of the same material.

  The reflective layer side interface layer, the first interface layer, and the second interface layer are the same as the reflective layer side interface layer 403, the first interface layer 405, and the second interface layer 407 of Embodiment 1, respectively. It has a function and can be formed of the same material.

The information recording medium 13 can be manufactured by the method described below.
First, the first information layer 41 is formed on the substrate 21 (thickness is, for example, 1.1 mm).
Specifically, first, the reflective layer 412 is formed on the substrate 21. The reflective layer 412 can be formed by a method similar to the method for forming the reflective layer 402 in Embodiment 1.

  Subsequently, a reflective layer side interface layer is formed on the reflective layer 412 as necessary. The reflective layer side interface layer can be formed by a method similar to the method of forming the reflective layer side interface layer 403 of the first embodiment.

  Subsequently, a first dielectric layer 414 is formed on the reflective layer side interface layer or on the reflective layer 412. The first dielectric layer 414 can be formed by a method similar to the method for forming the first dielectric layer 404 of the first embodiment.

  Subsequently, a first interface layer is formed on the first dielectric layer 414 as necessary. The first interface layer can be formed by a method similar to that of the first interface layer 405 in Embodiment 1.

  Subsequently, a recording layer 416 is formed on the first interface layer or on the first dielectric layer 414. When Sb and S are included, the recording layer 416 can be formed by a method similar to the method for forming the recording layer 406 of Embodiment 1. In the case where the recording layer 416 is formed of another material, a sputtering target may be selected according to the material and formed by a sputtering method.

  Subsequently, a second interface layer is formed on the recording layer 416 as necessary. The second interface layer can be formed by a method similar to the method for forming the second interface layer 407 in Embodiment 1.

  Subsequently, a second dielectric 418 is formed on the second interface layer or the recording layer 416. The second dielectric layer 418 can be formed by a method similar to the method for forming the second dielectric layer 408 of Embodiment 1.

  In this way, the first information layer 41 is formed on the substrate 21, and then the separation layer 22 is formed on the first information layer 41. The separation layer 22 can be formed by the method described in the second embodiment.

  Note that after the second dielectric layer 418 is formed or the separation layer 22 is formed, an initialization process for crystallizing the recording layer 416 may be performed by irradiating a laser beam as necessary. Good.

Subsequently, the second information layer 42 is formed on the separation layer 22.
Specifically, the transmittance adjusting layer 421 is first formed on the separation layer 22. The transmittance adjusting layer 421 can be formed by a method similar to the method for forming the transmittance adjusting layer 491 of Embodiment 2.

  Subsequently, a reflective layer 422 is formed on the transmittance adjusting layer 421. The reflective layer 422 can be formed by a method similar to the method for forming the reflective layer 492 of Embodiment 2.

  Subsequently, a reflective layer side interface layer is formed on the reflective layer 422 as necessary. The reflective layer side interface layer can be formed by a method similar to the method of forming the reflective layer side interface layer of the second embodiment.

  Subsequently, the first dielectric layer 424 is formed on the reflective layer side interface layer or on the reflective layer 422. The first dielectric layer 424 can be formed by a method similar to the method for forming the first dielectric layer 494 of Embodiment 2.

  Subsequently, a first interface layer is formed on the first dielectric layer 424 as necessary. The first interface layer can be formed by a method similar to the method for forming the first interface layer in the second embodiment.

  Subsequently, a recording layer 426 is formed on the first interface layer or on the first dielectric layer 424. The recording layer 426 can be formed by a method similar to the method for forming the recording layer 496 of Embodiment 2.

  Subsequently, a second interface layer is formed on the recording layer 426 as necessary. The second interface layer can be formed by a method similar to the method for forming the second interface layer of the second embodiment.

  Subsequently, a second dielectric 428 is formed on the second interface layer or the recording layer 426. The second dielectric layer 428 can be formed by a method similar to the method for forming the second dielectric layer 498 of Embodiment 2.

  In this way, the second information layer 42 is formed on the separation layer 22, and then the transparent layer 23 is formed on the second information layer 42. The transparent layer 23 can be formed by the method described in the first embodiment.

  Since each recording layer of the information recording medium 13 is normally in an amorphous state as it is formed, an initialization process for crystallizing the recording layer by irradiating a laser beam as necessary is performed. You may go. Alternatively, when the recording layer 416 has already been initialized, only the recording layer 426 may be initialized after the second information layer 42 is formed.

  The information recording medium 13 can be manufactured as described above. In the present embodiment, a sputtering method is used as a method for forming each layer constituting the information layer. The formation method is not limited to this, and a vacuum deposition method, an ion plating method, an MBE method, or the like can also be used.

  If N is 2 and a laser beam in the blue-violet region near the wavelength of 405 nm is used for recording and reproduction, and the capacity per information layer is about 25 GB, an information recording medium having a capacity of about 50 GB can be obtained. . Alternatively, if the recording density is increased and the capacity per information layer is about 33 GB, an information recording medium having a capacity of about 66 GB can be obtained.

(Embodiment 4)
As Embodiment 4, an example of an information recording medium in which N = 4, that is, four information layers in the multilayer information recording medium of the present invention of Embodiment 2 will be described. FIG. 5 shows a partial cross-sectional view of the information recording medium 14 according to the fourth embodiment. The information recording medium 14 is a four-layer optical recording medium, and information is recorded and reproduced by condensing and irradiating the laser beam 31 with an objective lens 32.

  In the information recording medium 14, the first information layer 41, the separation layer 22, the second information layer 42, the separation layer 28, the third information layer 43, the separation layer 29, the fourth information layer 44, and the transparent layer are formed on the substrate 21. 23 are provided in this order.

  In the information recording medium 12, the laser beam reaching the information layer closer to the substrate 21 than the fourth information layer 44 and the reflected light are attenuated by passing through the information layer closer to the laser beam 31 incident side than the information layer. Resulting in. Therefore, the first information layer 41, the second information layer 42, and the third information layer 43 have high recording sensitivity and high reflectance, and the second information layer 42, the third information layer 43, and the fourth information layer. 44 needs to have a high transmittance.

  The substrate 21, the separation layers 22, 28, 29 and the transparent layer 23 can be formed using the same materials as those described in the first and second embodiments. In addition, their shapes and functions are as described in the first and second embodiments.

  Since the material, shape, and function of each layer constituting the first information layer 41 are as described in the third embodiment, detailed description thereof is omitted.

  The fourth information layer 44 plays the same role as the Nth information layer 49 described in the second embodiment (since N = 4 in the fourth embodiment). Therefore, each layer constituting the fourth information layer 44 can be formed of the material of each layer constituting the Nth information layer 49 described in the second embodiment. The shape and function of each layer constituting the fourth information layer 44 are the same as the shape and function of each layer constituting the Nth information layer 49 described in the second embodiment.

Hereinafter, the configurations of the second information layer 42 and the third information layer 43 will be described.
In the second information layer 42, a transmittance adjusting layer 421, a reflective layer 422, a first dielectric layer 424, a recording layer 426, and a second dielectric layer 428 are provided in this order from the side close to the substrate 21. . Further, if necessary, a reflective layer side interface layer is provided between the reflective layer 422 and the first dielectric layer 424, and a first interface layer is provided between the first dielectric layer 424 and the recording layer 426. A second interface layer may be provided between the second dielectric layer 428 and the recording layer 426. In FIG. 5, the reflective layer side interface layer can be shown as a layer represented by 423 between the layers 422 and 424, and the first interface layer can be represented by 425 between the layers 424 and 426. The second interface layer can be shown as a layer represented by 427 between layers 426 and 428.

  The recording layer 426, the reflective layer 422, the first dielectric layer 424, the second dielectric layer 428, and the transmittance adjusting layer 421 are the recording layer 496, the reflective layer 492, and the first dielectric, respectively, of the second embodiment. The layer 494, the second dielectric layer 498, and the transmittance adjusting layer 491 have the same functions and can be formed using the same material.

  The reflective layer side interface layer, the first interface layer, and the second interface layer have the same functions as the reflective layer side interface layer, the first interface layer, and the second interface layer, respectively, of the second embodiment. However, it can be formed of the same material.

  In the third information layer 43, a transmittance adjusting layer 431, a reflective layer 432, a first dielectric layer 434, a recording layer 436, and a second dielectric layer 438 are provided in this order from the side close to the substrate 21. Yes. Further, if necessary, a reflective layer side interface layer is provided between the reflective layer 432 and the first dielectric layer 434, and a first interface layer is provided between the first dielectric layer 434 and the recording layer 436. A second interface layer may be provided between the second dielectric layer 438 and the recording layer 436. In FIG. 5, the reflective layer side interface layer can be shown as a layer represented by 433 between the layers 432 and 424, and the first interface layer can be represented by 435 between the layers 434 and 436. The second interface layer can be shown as a layer represented by 437 between the layers 436 and 438.

  The recording layer 436, the reflective layer 432, the first dielectric layer 434, the second dielectric layer 438, and the transmittance adjusting layer 431 are the recording layer 496, the reflective layer 492, and the first dielectric, respectively, according to the second embodiment. The layer 494, the second dielectric layer 498, and the transmittance adjusting layer 491 have the same functions and can be formed using the same material.

  The reflective layer side interface layer 433, the first interface layer, and the second interface layer have the same functions as the reflective layer side interface layer, the first interface layer, and the second interface layer of the second embodiment, respectively. And can be formed of the same material.

  In the medium of this mode, the recording layer included in any one of the three information layers from the second information layer 42 to the fourth information layer 44 includes Sb and S, and the above formula (1 It is preferable that the material shown in any of (4)-(4) is included. The reason is as described in connection with the second embodiment.

The information recording medium 14 can be manufactured by the method described below.
First, the first information layer 41 is formed on the substrate 21 (thickness is, for example, 1.1 mm).
Specifically, the reflective layer 412, the first dielectric layer 414, the recording layer 416, and the second dielectric layer 418 are formed in this order on the substrate 21. At this time, if necessary, the reflective layer side interface layer is provided between the reflective layer 412 and the first dielectric layer 414, and the first interface layer is provided between the first dielectric layer 414 and the recording layer 416. A second interface layer may be formed between the second dielectric layer 418 and the recording layer 416. Each of these layers can be formed by the method described in Embodiment Mode 3.

  In this way, the first information layer 41 is formed on the substrate 21, and then the separation layer 22 is formed on the first information layer 41. The separation layer 22 can be formed by the method described in the second embodiment.

  After the second dielectric layer 418 is formed or the separation layer 22 is formed, an initialization process for crystallizing the recording layer 416 may be performed by irradiating a laser beam, if necessary.

Subsequently, the second information layer 42 is formed on the separation layer 22.
Specifically, first, the transmittance adjustment layer 421 is formed on the separation layer 22. The transmittance adjusting layer 421 can be formed by a method similar to the method for forming the transmittance adjusting layer 491 of Embodiment 2.

  Subsequently, a reflective layer 422 is formed on the transmittance adjusting layer 421. The reflective layer 422 can be formed by a method similar to the method for forming the reflective layer 492 of Embodiment 2.

  Subsequently, a reflective layer side interface layer is formed on the reflective layer 422 as necessary. The reflective layer side interface layer can be formed by the same method as the reflective layer side interface layer of the second embodiment.

  Subsequently, the first dielectric layer 424 is formed on the reflective layer side interface layer or on the reflective layer 422. The first dielectric layer 424 can be formed by a method similar to the method for forming the first dielectric layer 494 of Embodiment 2.

  Subsequently, a first interface layer is formed on the first dielectric layer 424 as necessary. The first interface layer can be formed by a method similar to the method for forming the first interface layer in the second embodiment.

  Subsequently, a recording layer 426 is formed on the first interface layer or on the first dielectric layer 424. The recording layer 426 can be formed by a method similar to the method for forming the recording layer 496 of Embodiment 2.

  Subsequently, a second interface layer is formed on the recording layer 426 as necessary. The second interface layer can be formed by a method similar to the method for forming the second interface layer of the second embodiment.

  Subsequently, a second dielectric 428 is formed on the second interface layer or the recording layer 426. The second dielectric layer 428 can be formed by a method similar to the method for forming the second dielectric layer 498 of Embodiment 2.

  In this way, the second information layer 42 is formed on the separation layer 22, and then the separation layer 28 is formed on the second information layer 42. The separation layer 28 can be formed by the method described in the second embodiment.

  Note that after the second dielectric layer 428 is formed or the separation layer 28 is formed, an initialization process for crystallizing the recording layer 426 may be performed by irradiating a laser beam, if necessary. Good.

Subsequently, the third information layer 43 is formed on the separation layer 28.
Specifically, first, the transmittance adjusting layer 431 is formed on the separation layer 28. The transmittance adjustment layer 431 can be formed by a method similar to the method for forming the transmittance adjustment layer 491 of Embodiment 2.

  Subsequently, the reflective layer 432 is formed on the transmittance adjusting layer 431. The reflective layer 432 can be formed by a method similar to the method for forming the reflective layer 492 in Embodiment 2.

  Subsequently, a reflective layer side interface layer is formed on the reflective layer 432 as necessary. The reflective layer side interface layer can be formed by a method similar to the method of forming the reflective layer side interface layer of the second embodiment.

  Subsequently, a first dielectric layer 434 is formed on the reflective layer side interface layer or on the reflective layer 432. The first dielectric layer 434 can be formed by a method similar to the method for forming the first dielectric layer 494 of the second embodiment.

  Subsequently, a first interface layer is formed on the first dielectric layer 434 as necessary. The first interface layer can be formed by a method similar to the method for forming the first interface layer in the second embodiment.

  Subsequently, a recording layer 436 is formed on the first interface layer or on the first dielectric layer 434. The recording layer 436 can be formed by a method similar to the method for forming the recording layer 496 of Embodiment 2.

  Subsequently, a second interface layer is formed on the recording layer 436 as necessary. The second interface layer can be formed by a method similar to the method for forming the second interface layer of the second embodiment.

  Subsequently, a second dielectric 438 is formed on the second interface layer or the recording layer 436. The second dielectric layer 438 can be formed by a method similar to that of the second dielectric layer 498 of the second embodiment.

  In this way, the third information layer 43 is formed on the separation layer 28, and then the separation layer 29 is formed on the third information layer 43. The separation layer 29 can be formed by the method described in the second embodiment.

  Note that after the second dielectric layer 438 is formed or after the separation layer 29 is formed, an initialization process for crystallizing the recording layer 436 may be performed by irradiating a laser beam as necessary. good.

Subsequently, the fourth information layer 44 is formed on the separation layer 29.
Specifically, the transmittance adjusting layer 441, the reflective layer 442, the first dielectric layer 444, the recording layer 446, and the second dielectric layer 448 are formed on the separation layer 29 in this order. At this time, if necessary, the reflective layer side interface layer is provided between the reflective layer 442 and the first dielectric layer 444, and the first interface layer is provided between the first dielectric layer 444 and the recording layer 446. A second interface layer may be formed between the second dielectric layer 448 and the recording layer 446. Each of these layers can be formed by the method described in Embodiment Mode 2.

  In this way, the fourth information layer 44 is formed on the separation layer 29, and then the transparent layer 23 is formed on the fourth information layer 44. The transparent layer 23 can be formed by the method described in the first embodiment.

  Since each recording layer of the information recording medium 14 is normally in an amorphous state as it is formed, an initialization process for crystallizing the recording layer by irradiating a laser beam as necessary. You may do. Alternatively, when the recording layers 416, 426, and 436 are already initialized, only the recording layer 446 may be initialized after the fourth information layer 44 is formed.

  The information recording medium 14 can be manufactured as described above. In the present embodiment, a sputtering method is used as a method for forming each layer constituting the information layer. The formation method is not limited to this, and a vacuum deposition method, an ion plating method, an MBE method, or the like can also be used.

  If N is 4 and a laser beam in the blue-violet region near the wavelength of 405 nm is used for recording and reproduction, and the capacity per information layer is about 25 GB, an information recording medium having a capacity of about 100 GB can be obtained. . Alternatively, if the recording density is increased so that the capacity per information layer is about 33 GB, an information recording medium having a capacity of about 133 GB can be obtained.

  As the third and fourth embodiments, the media of N = 2 and 4 have been described. N may be 3. The medium of N = 3 includes the substrate 21, the first information layer 42, the separation layer 22, the second information layer 42, the separation layer 28, the third information layer 43, and the transparent layer 23 among the layers shown in FIG. Is done. In the medium of N = 3, the recording layer included in one or both of the second information layer and the third information layer includes Sb and S, and any one of formulas (1) to (4) It is preferable that the material shown by these is included. Further, when only the recording layer included in the third information layer closest to the laser beam incident side is a recording layer including the material represented by any one of the formulas (1) to (4), including Sb and S. In addition, the effects of the present invention can be sufficiently obtained.

  If N is 3 and a laser beam in the blue-violet region near the wavelength of 405 nm is used for recording and reproduction, and the capacity per information layer is about 25 GB, an information recording medium having a capacity of about 75 GB can be obtained. . Alternatively, if the recording density is increased and the capacity per information layer is about 33 GB, an information recording medium having a capacity of about 100 GB can be obtained.

(Embodiment 5)
As Embodiment 5, another example of the information recording medium of the present invention will be described. FIG. 6 shows a partial cross-sectional view of the information recording medium 15 of the fifth embodiment. The information recording medium 15 is an optical recording medium, and information can be recorded and reproduced by condensing and irradiating the laser beam 31 with the objective lens 32.

  The information recording medium 15 is configured such that the information layer 40 laminated on the substrate 24 and the dummy substrate 26 are in close contact via an adhesive layer 27.

  The substrate 24 and the dummy substrate 26 are transparent and have a disk shape. A guide groove for guiding the laser beam 31 may be formed on the surface of the substrate 24 in contact with the information layer 40. The surface that does not contact the information layer 40 of the substrate 24 and the surface that does not contact the adhesive layer 27 of the dummy substrate are preferably smooth. The substrate 24 and the dummy substrate 26 can be formed using polycarbonate resin, polymethyl methacrylate resin, polyolefin resin, norbornene resin, glass, or a combination of these as materials. In particular, a polycarbonate resin is preferable as a material for the substrate 24 and the dummy substrate 26 because it is excellent in transferability and mass productivity and is low in cost.

  The adhesive layer 27 preferably has a small light absorption with respect to the laser beam 31. The adhesive layer 27 is made of polycarbonate resin, polymethyl methacrylate resin, polyolefin resin, norbornene resin, ultraviolet curable resin (for example, acrylic resin and epoxy resin), slow-acting thermosetting resin, glass, or a combination thereof. It can be formed using materials such as

  Since the material, shape and function of each layer constituting the information layer 40 are as described in the first embodiment, detailed description thereof will be omitted. In addition, the description about the element which attached | subjected the code | symbol same as the code | symbol used in Embodiment 1 is abbreviate | omitted.

The information recording medium 15 can be manufactured by the method described below.
First, the information layer 40 is formed on the substrate 24 (thickness is, for example, 0.6 mm). Specifically, the second dielectric layer 408, the recording layer 406, the first dielectric layer 404, and the reflective layer 402 are formed on the substrate 24 in this order. At this time, if necessary, a second interface layer is provided between the second dielectric layer 408 and the recording layer 406, and a first interface layer is provided between the first dielectric layer 404 and the recording layer 406. Alternatively, a reflective layer-side interface layer may be formed between the first dielectric layer 404 and the reflective layer 402. In FIG. 5, the second interface layer can be shown as a layer represented by 407 between layers 408 and 406, and the first interface layer can be shown as 405 between layers 406 and 404. The reflective layer side interface layer can be represented as a layer represented by 403 between the layers 402 and 404. Each of these layers can be formed by the method described in Embodiment Mode 1.

  Next, the substrate 24 on which the information layer 40 is laminated and the dummy substrate 26 (having a thickness of, for example, 0.6 mm) are bonded using the adhesive layer 27. Specifically, the bonding is performed by applying an ultraviolet curable resin or a slow-acting thermosetting resin on the dummy substrate 26 by a spin coating method, and closely attaching the substrate 24 on which the information layer 40 is laminated to the dummy substrate 26. And then by a method of curing the resin. Alternatively, an adhesive resin can be uniformly applied on the dummy substrate 26 in advance, and the dummy substrate 26 can be adhered to the substrate 24 on which the information layer 40 is laminated.

  The recording layer 406 of the information recording medium 15 is normally in an amorphous state as it is formed. Therefore, an initialization process for crystallizing the recording layer 406 may be performed by irradiating a laser beam, if necessary.

  The information recording medium 15 can be manufactured as described above. In the present embodiment, a sputtering method is used as a method for forming each layer constituting the information layer. The formation method is not limited to this, and a vacuum deposition method, an ion plating method, an MBE method, or the like can also be used.

(Embodiment 6)
As Embodiment 6, another example of the information recording medium of the present invention will be described. FIG. 7 shows a partial sectional view of the information recording medium 16 of the sixth embodiment. The information recording medium 16 is a multilayer optical recording medium, and information is recorded and reproduced by condensing and irradiating the laser beam 31 with an objective lens 32.

  The information recording medium 16 includes N-1 information layers (N is N) up to the Nth information layer 49, the N-1th information layer 48,. The integer of ≧ 2) and the first information layer 41 laminated on the substrate 25 are in close contact with each other through the adhesive layer 27. The separation layers 29, 28, etc. are interposed between the information layers.

  The substrate 25 is transparent and has a disk shape. A guide groove for guiding the laser beam 31 may be formed on the surface of the substrate 25 in contact with the first information layer 41. The surface of the substrate 25 that does not contact the first information layer 41 is preferably smooth. The substrate 25 can be formed using a polycarbonate resin, a polymethyl methacrylate resin, a polyolefin resin, a norbornene-based resin, glass, or a combination of these as a material. In particular, a polycarbonate resin is preferable as a material for the substrate 25 because it is excellent in transferability and mass productivity and is low in cost.

  In addition, the description about the element which attached | subjected the code | symbol same as the code | symbol used in Embodiment 2 and 5 is abbreviate | omitted.

The information recording medium 16 can be manufactured by the method described below.
First, the Nth information layer 49 is formed on the substrate 24 (thickness is, for example, 0.6 mm). Specifically, the second dielectric layer 498, the recording layer 496, the first dielectric layer 494, the reflective layer 492, and the transmittance adjusting layer 491 are formed on the substrate 24 in this order. At this time, if necessary, a second interface layer is provided between the second dielectric layer 498 and the recording layer 496, and a first interface layer is provided between the first dielectric layer 494 and the recording layer 496. Alternatively, a reflective layer side interface layer may be formed between the first dielectric layer 494 and the reflective layer 492. Each of these layers can be formed by the method described in Embodiment Mode 2. Thereafter, the N-1 information layer 48 to the second information layer 42 are sequentially stacked via the separation layers 29, 28,.

  Separately, the first information layer 41 is formed on the substrate 25 (thickness is, for example, 0.6 mm). The information layer is generally composed of a multilayer film, and each layer (film) constituting the information layer 41 is sequentially sputtered with a sputtering target suitable for constituting each layer in the film forming apparatus as in the second embodiment. Can be formed.

  Finally, the substrate 24 and the substrate 25 on which the information layer is stacked are bonded using the adhesive layer 27. Specifically, the bonding is performed by applying an ultraviolet curable resin or a slow-acting thermosetting resin to the first information layer 41 laminated on the substrate 25 by a spin coating method, and the second information layer 42 is laminated. The substrate 24 may be adhered to the first information layer 41, and then the resin may be cured. Alternatively, an adhesive resin can be applied uniformly on the first information layer 41 in advance, and the first information layer 41 can be adhered to the substrate 24 on which the second information layer 42 is laminated.

  Since each recording layer of the information recording medium 16 is normally in an amorphous state as it is formed, an initialization process for crystallizing the recording layer by irradiating a laser beam as necessary is performed. You may go.

  The information recording medium 16 can be manufactured as described above. In the present embodiment, a sputtering method is used as a method for forming each layer constituting the information layer. The formation method is not limited to this, and a vacuum deposition method, an ion plating method, an MBE method, or the like can also be used.

(Embodiment 7)
As Embodiment 7, an example of an information recording medium in which N is 2 in the multilayer information recording medium of the present invention of Embodiment 6, that is, constituted by two information layers will be described. FIG. 8 shows a partial sectional view of the information recording medium 17 according to the seventh embodiment. The information recording medium 17 is a two-layer optical recording medium, and information is recorded and reproduced by collecting and irradiating the laser beam 31 with an objective lens 32.

  The information recording medium 17 is configured such that the second information layer 42 stacked on the substrate 24 and the first information layer 41 stacked on the substrate 25 are in close contact with each other through the adhesive layer 27.

  Since the materials, shapes, and functions of the layers constituting the first information layer 41 and the second information layer 42 are as described in the third embodiment, detailed description thereof is omitted here. In addition, the description about the element which attached | subjected the code | symbol same as the code | symbol used in Embodiment 3, 5, and 6 is abbreviate | omitted.

The information recording medium 17 can be manufactured by the method described below.
First, the second information layer 42 is formed on the substrate 24 (having a thickness of, for example, 0.6 mm). Specifically, the second dielectric layer 428, the recording layer 426, the first dielectric layer 424, the reflective layer 422, and the transmittance adjusting layer 421 are formed on the substrate 24 in this order. At this time, if necessary, a second interface layer is provided between the second dielectric layer 428 and the recording layer 426, and a first interface layer is provided between the first dielectric layer 424 and the recording layer 426. Alternatively, a reflective layer-side interface layer may be formed between the first dielectric layer 424 and the reflective layer 422. Each of these layers can be formed by the method described in Embodiment Mode 3.

  After the transmittance adjusting layer 421 is formed, an initialization process for crystallizing the recording layer 426 may be performed by irradiating a laser beam as necessary.

  Separately, the first information layer 41 is formed on the substrate 25 (thickness is, for example, 0.6 mm). Specifically, the reflective layer 412, the first dielectric layer 414, the recording layer 416 and the second dielectric layer 418 are formed on the substrate 25 in this order. At this time, if necessary, the reflective layer side interface layer is provided between the reflective layer 412 and the first dielectric layer 414, and the first interface layer is provided between the first dielectric layer 414 and the recording layer 416. A second interface layer may be formed between the second dielectric layer 418 and the recording layer 416. Each of these layers can be formed by the method described in Embodiment Mode 3.

  After the second dielectric layer 418 is formed, an initialization process for crystallizing the recording layer 416 may be performed by irradiating a laser beam, if necessary.

  Finally, the substrate 24 and the substrate 25 on which the information layer is stacked are bonded using the adhesive layer 27. Specifically, the bonding is performed by applying an ultraviolet curable resin (for example, acrylic resin and epoxy resin) or a slow-acting thermosetting resin to the first information layer 41 laminated on the substrate 25 by a spin coat method. Application may be performed by a method in which the substrate 24 on which the second information layer 42 is laminated is brought into close contact with the first information layer 41 and then the resin is cured. Alternatively, an adhesive resin can be applied uniformly on the first information layer 41 in advance, and the first information layer 41 can be adhered to the substrate 24 on which the second information layer 42 is laminated.

  Since each recording layer of the information recording medium 17 is normally in an amorphous state as it is formed, an initialization process for crystallizing the recording layer by irradiating a laser beam as necessary is performed. You may go. In the case where the recording layers 416 and 426 are initialized in advance, it is not necessary to perform an initialization process after bonding.

  The information recording medium 17 can be manufactured as described above. In the present embodiment, a sputtering method is used as a method for forming each layer constituting the information layer. The formation method is not limited to this, and a vacuum deposition method, an ion plating method, an MBE method, or the like can also be used.

  The medium in which N is 2 can have a capacity of about 50 GB, for example, or can have a capacity of about 66 GB, as described above in connection with the seventh embodiment.

(Embodiment 8)
As an eighth embodiment, an example of an information recording medium in which N is 4 in the multilayer information recording medium of the present invention according to the sixth embodiment, that is, an information recording medium constituted by four information layers will be described. FIG. 9 shows a partial cross-sectional view of the information recording medium 18 according to the eighth embodiment. The information recording medium 18 is a four-layer optical recording medium capable of recording and reproducing information by condensing and irradiating a laser beam 31 with an objective lens 32.

  In the information recording medium 18, the fourth information layer 44, the third information layer 43 and the second information layer 42 stacked on the substrate 24, and the first information layer 41 stacked on the substrate 25 are interposed via the adhesive layer 27. The structure is closely attached. A separation layer 29 is provided between the fourth information layer 44 and the third information layer 43, and a separation layer 28 is provided between the third information layer 43 and the second information layer.

  The materials, shapes, and functions of the respective layers constituting the first information layer 41, the second information layer 42, the third information layer 43, and the fourth information layer 44 are as described in the fourth embodiment. Detailed description is omitted. In addition, the description about the element which attached | subjected the code | symbol same as the code | symbol used in Embodiment 4, 5, 6, and 7 is abbreviate | omitted.

The information recording medium 18 can be manufactured by the method described below.
First, the fourth information layer 44 is formed on the substrate 24 (thickness is, for example, 0.6 mm). Specifically, the second dielectric layer 448, the recording layer 446, the first dielectric layer 444, the reflective layer 442, and the transmittance adjusting layer 441 are formed on the substrate 24 in this order. At this time, if necessary, a second interface layer is provided between the second dielectric layer 448 and the recording layer 446, and a first interface layer is provided between the first dielectric layer 444 and the recording layer 446. Alternatively, a reflective layer side interface layer may be formed between the first dielectric layer 444 and the reflective layer 442. Each of these layers can be formed by the method described in connection with the fourth embodiment.

  Subsequently, the separation layer 29 is formed on the transmittance adjusting layer 441 by the method described in connection with the fourth embodiment.

  After the transmittance adjusting layer 441 is formed or the separation layer 29 is formed, an initialization process for crystallizing the recording layer 446 may be performed by irradiating a laser beam, if necessary.

  Subsequently, the third information layer 43 is formed on the separation layer 29. Specifically, the second dielectric layer 438, the recording layer 436, the first dielectric layer 434, the reflective layer 432, and the transmittance adjusting layer 431 are formed on the separation layer 29 in this order. At this time, if necessary, a second interface layer is provided between the second dielectric layer 438 and the recording layer 436, and a first interface layer is provided between the first dielectric layer 434 and the recording layer 436. Alternatively, a reflective layer side interface layer may be formed between the first dielectric layer 434 and the reflective layer 432. Each of these layers can be formed by the method described in connection with the fourth embodiment.

  Subsequently, the separation layer 28 is formed on the transmittance adjusting layer 431 by the method described in connection with the fourth embodiment.

  After the transmittance adjusting layer 431 is formed or the separation layer 28 is formed, an initialization process for crystallizing the recording layer 436 may be performed by irradiating a laser beam, if necessary.

  Subsequently, the second information layer 42 is formed on the separation layer 28. Specifically, the second dielectric layer 428, the recording layer 426, the first dielectric layer 424, the reflective layer 422, and the transmittance adjusting layer 421 are formed on the substrate 24 in this order. At this time, if necessary, a second interface layer is provided between the second dielectric layer 428 and the recording layer 426, and a first interface layer is provided between the first dielectric layer 424 and the recording layer 426. Alternatively, a reflective layer side interface layer may be formed between the first dielectric layer 424 and the reflective layer 422. Each of these layers can be formed by the method described in connection with the fourth embodiment.

  After the transmittance adjusting layer 421 is formed, an initialization process for crystallizing the recording layer 426 may be performed by irradiating a laser beam as necessary.

  Separately, the first information layer 41 is formed on the substrate 25 (thickness is, for example, 0.6 mm). Specifically, the reflective layer 412, the first dielectric layer 414, the recording layer 416 and the second dielectric layer 418 are formed on the substrate 25 in this order. At this time, if necessary, the reflective layer side interface layer is provided between the reflective layer 412 and the first dielectric layer 414, and the first interface layer is provided between the first dielectric layer 414 and the recording layer 416. A second interface layer may be formed between the second dielectric layer 418 and the recording layer 416. Each of these layers can be formed by the method described in connection with the fourth embodiment.

  After the second dielectric layer 418 is formed, an initialization process for crystallizing the recording layer 416 may be performed by irradiating a laser beam, if necessary.

  Finally, the substrate 24 and the substrate 25 on which the information layer is stacked are bonded using the adhesive layer 27. Specifically, the bonding is performed by applying an ultraviolet curable resin (for example, acrylic resin and epoxy resin) or a slow-acting thermosetting resin to the first information layer 41 laminated on the substrate 25 by a spin coat method. Application may be performed by a method in which the substrate 24 on which the second information layer 42 is laminated is brought into close contact with the first information layer 41 and then the resin is cured. Alternatively, an adhesive resin can be applied uniformly on the first information layer 41 in advance, and the first information layer 41 can be adhered to the substrate 24 on which the second information layer 42 is laminated.

  Since each recording layer of the information recording medium 18 is normally in an amorphous state as it is formed, an initialization process for crystallization by irradiating a laser beam or the like may be performed as necessary. . When the recording layers 416, 426, 436, and 446 are initialized in advance, it is not necessary to perform an initialization process after the bonding.

  The information recording medium 18 can be manufactured as described above. In the present embodiment, a sputtering method is used as a method for forming each layer constituting the information layer. The formation method is not limited to this, and a vacuum deposition method, an ion plating method, an MBE method, or the like can also be used.

  In the present embodiment, the substrate 24 and the substrate 25 are bonded together using the adhesive layer 27 between the second information layer 42 and the first information layer 41. The position of the adhesive layer, that is, the bonding position is not limited to this.

  For example, the fourth information layer 44 and the third information layer 43 are laminated on the substrate 24 via the separation layer 29, and the separation layer (the position is the position of the adhesive layer 27 in FIG. 9) on the substrate 25. Then, the first information layer 41 and the second information layer 42 are stacked, and then the adhesive layer (the position is the position of the separation layer 28 in FIG. 9) between the third information layer 43 and the second information layer 42. ) To bond the substrate 24 and the substrate 25 together.

  The medium in which N is 4 can have a capacity of about 100 GB, for example, or can have a capacity of about 133 GB, as described above in connection with the eighth embodiment.

  As Embodiments 7 and 8 having two substrates and a plurality of information layers, the media of N = 2 and 4 have been described. N may be 3. In the medium of N = 3, the recording layer included in one or both of the second information layer and the third information layer includes Sb and Sn, and any one of formulas (1) to (4) It is preferable that the material shown by these is included. Further, only the recording layer included in the third information layer closest to the laser beam incident side includes the Sb and Sn, and includes a material represented by any one of the formulas (1) to (4). The effects of the present invention can be sufficiently obtained.

  A medium where N is 3 can have a capacity of about 75 GB, for example, as described above, or can have a capacity of about 100 GB.

(Embodiment 9)
In the ninth embodiment, an example of a method for recording information on the information recording medium described in the first to eighth embodiments and / or reproducing the information recorded on the medium will be described.
FIG. 10 shows a schematic diagram of an example of the configuration of a recording / reproducing apparatus used for recording / reproducing of the information recording medium of the present invention. The laser beam 502 emitted from the laser diode 501 passes through the half mirror 503 and the objective lens 504 and is focused on the information recording medium 506. The information recording medium 506 is rotated by a motor 505. Information reproduction is performed by causing reflected light from the information recording medium 506 to enter the photodetector 507 and detecting a signal.

  When recording an information signal, the intensity of the laser beam 502 is modulated between a plurality of power levels. As a means for modulating the laser intensity, a current modulation means for modulating the driving current of the semiconductor laser can be used. A portion where the recording mark is formed may be irradiated with a single rectangular pulse laser beam having a peak power Pp. Alternatively, when a particularly long mark is formed, the peak power Pp and the bottom power Pb (provided that Pp as shown in FIG. 11) are used to prevent the recording layer from being overheated and to make the mark width uniform. A recording pulse train composed of a plurality of pulse trains modulated with respect to> Pb) may be used. Further, a cooling section in which the laser power is set to the cooling power Pc (Pc <Pb) may be provided after the last pulse. A portion where no mark is formed is irradiated with a laser beam having a bias power Pe (where Pp> Pe).

  The numerical aperture NA of the objective lens 504 is preferably in the range of 0.5 to 1.1 in order to adjust the spot diameter of the laser beam 502 in the range of 0.4 μm to 0.7 μm, and 0.6 More preferably, it is in the range of -0.9. The wavelength of the laser beam 502 is preferably in the range of 350 nm to 450 nm. The linear velocity of the information recording medium 506 at the time of recording information is preferably within a range of 4 m / s to 50 m / s so that recrystallization hardly occurs and sufficient erasing performance is obtained. More preferably, it is in the range of / s to 40 m / s. It goes without saying that the wavelength, the numerical aperture of the objective lens, and the linear velocity not illustrated here may be used depending on the type of the information recording medium 502 and the like. For example, the wavelength of the laser beam 502 may be 650 to 670 nm.

  Using such a recording / reproducing apparatus, the performance of the information recording medium 506 can be evaluated as follows.

  The recording performance is that the laser beam 502 is power-modulated between 0 and Pp (mW), and a random signal with a mark length of 0.149 μm (2T) to 0.596 μm (8T) is recorded by the (1-7) modulation method. Then, the jitter (mark position error) between the front end and the rear end of the recording mark can be evaluated by measuring with a time interval analyzer. Note that the smaller the jitter value, the better the recording performance. Pp, Pb, Pc and Pe are determined so that the average value of jitter between the front ends and between the rear ends is minimized. The determined Pp is the recording sensitivity.

  In addition, the signal intensity is obtained by power-modulating the laser beam 502 between 0 and Pp (mW), and recording signals with mark lengths of 0.149 μm (2T) and 0.671 μm (9T) alternately on the same track 10 times. The ratio of the signal amplitude at the frequency of the 2T signal and the noise level at the frequency of the 2T signal when the 2T signal is overwritten at the end can be evaluated by measuring with a spectrum analyzer (CNR (Carrier to Noise Ratio)). . The greater the CNR, the higher the signal strength.

  The erasing performance is 2T when the laser beam 502 is power modulated between 0 and Pp (mW), the 2T signal and the 9T signal are alternately recorded on the same track 10 times continuously, and the 2T signal is overwritten at the 11th time. The difference between the signal amplitude of the signal and the signal amplitude of the 2T signal when the 9T signal is overwritten thereafter can be evaluated by measuring with a spectrum analyzer as the erasure rate of the 2T signal. The larger the erase rate, the better the erase performance.

(Embodiment 10)
As Embodiment 10, another example of the information recording medium of the present invention will be described. One structural example of the information recording medium 61 of Embodiment 10 is shown in FIG. The information recording medium 61 is an electrical information recording medium in which information is recorded and reproduced by application of electrical energy (particularly current).

As the substrate 62, a resin substrate such as polycarbonate, a glass substrate, a ceramic substrate such as Al ₂ O ₃ , a semiconductor substrate such as Si, and a metal substrate such as Cu can be used. Here, an embodiment using a Si substrate as the substrate will be described. In the electrical information recording medium 61, a lower electrode 63, a first dielectric layer 64, a first recording layer 65, a second recording layer 66, a second dielectric layer 67, and an upper electrode 68 are sequentially stacked on a substrate 62. Structure. The lower electrode 63 and the upper electrode 68 are formed to apply a current to the first recording layer 65 and the second recording layer 66. The first dielectric layer 64 is provided for adjusting the amount of electric energy applied to the first recording layer 65, and the second dielectric layer 67 is provided for adjusting the amount of electric energy applied to the second recording layer 66. Examples of materials of the first dielectric layer 64 and the second dielectric layer 67 are the same as those of the material of the first dielectric layer 404 of the first embodiment.

  The first recording layer 65 and the second recording layer 66 are made of a material that causes a reversible phase change between a crystalline phase and an amorphous phase by Joule heat generated by application of current. Therefore, in this medium, a phenomenon in which the resistivity changes between the crystalline phase and the amorphous phase is used for information recording. At least one of the first recording layer 65 and the second recording layer 66 includes Sb and S, and includes a material represented by any of the above formulas (1) to (4). Such a material is as described in connection with the first embodiment. When any one of the recording layers is not a recording layer containing Sb and S, the material exemplified in connection with the second embodiment may be used. The first recording layer 65 and the second recording layer 66 are each formed by the same method as the recording layer 406 of the first embodiment or the recording layer 496 of the second embodiment.

The lower electrode 63 and the upper electrode 68 may be formed of a single metal material such as Ti, W, Al, Au, Ag, Cu, or Pt. Alternatively, the lower electrode 63 and the upper electrode 68 are mainly composed of one or more elements selected from the elements described above, and one or more other elements are appropriately added for improving moisture resistance or adjusting thermal conductivity. It can be formed using the added alloy material. The lower electrode 63 and the upper electrode 68 are made of a metal base material as a material in an Ar gas atmosphere or in a mixed gas atmosphere of Ar gas and a reactive gas (at least one gas selected from O ₂ gas or N ₂ gas). It can be formed by sputtering a material or an alloy base material. The formation method of each layer may be a vacuum deposition method, an ion plating method, a CVD method, an MBE method, or the like.

  An electrical information recording / reproducing device 74 is electrically connected to the electrical information recording medium 61 via an applying unit 69. In the electrical information recording / reproducing apparatus 74, a pulse power source 73 is connected between the lower electrode 63 and the upper electrode 68 in order to apply a current pulse to the first recording layer 65 and the second recording layer 66. Connected through. In addition, a resistance measuring device 70 is connected between the lower electrode 63 and the upper electrode 67 via a switch 72 in order to detect a change in resistance value due to a phase change of the first recording layer 65 and the second recording layer 66. The

  In order to change the first recording layer 65 or the second recording layer 66 in the amorphous phase (high resistance state) to the crystalline phase (low resistance state), the switch 71 is closed (the switch 72 is opened). A current pulse is applied between them. The application is performed so that the temperature of the portion to which the current pulse is applied is maintained during the crystallization time at a temperature higher than the crystallization temperature of the material and lower than the melting point. When returning from the crystalline phase to the amorphous phase again, a relatively high current pulse is applied in a shorter time than when crystallizing, the recording layer is heated to a temperature higher than the melting point, and then rapidly cooled. . The pulse power source 73 of the electrical information recording / reproducing apparatus 74 is a power source that can output the recording / erasing pulse waveform of FIG.

Here, the resistance value when the first recording layer 65 is in the amorphous phase is r _a1 , the resistance value when the first recording layer 65 is in the crystalline phase is r _c1 , and the second recording layer 66 is in the amorphous phase. In this case, the resistance value is r _a2 , and the resistance value when the second recording layer 66 is in the crystalline phase is r _c2 . r _c1 ≦ r _c2 <r _a1 <r _a2 , or r _c1 ≦ r _c2 <r _a2 <r _a1 , or r _c2 ≦ r _c1 <r _a1 <r _a2 , or r _c2 ≦ r _c1 <r _a2 <r _a1 Therefore, the sum of the resistance values of the first recording layer 65 and the second recording layer 66 is changed to four different values of r _a1 + r _a2 , r _a1 + r _{c 2} , r _a2 + r _c1 , and r _c1 + r _c2. Can be set. Therefore, by measuring the resistance value between the electrodes with the resistance measuring device 70, four different states, that is, binary information can be detected at a time.

  By arranging a large number of electrical information recording media 61 in a matrix, a large-capacity electrical information recording medium 81 as shown in FIG. 14 can be configured. Each memory cell 77 has a configuration similar to that of the electrical information recording medium 61 in a minute area. Information is recorded / reproduced in / from each memory cell 77 by designating one word line 75 and one bit line 76 respectively.

  FIG. 13 shows a configuration example of an information recording system using an electrical information recording medium 81. The storage device 79 includes an electrical information recording medium 81 and an address specifying circuit 78. The address designation circuit 78 designates the word line 75 and the bit line 76 of the electrical information recording medium 81, and information can be recorded on and reproduced from each memory cell 77. In addition, by electrically connecting the storage device 79 to an external circuit 80 including at least the pulse power source 73 and the resistance measuring device 70, information can be recorded on and reproduced from the electrical information recording medium 81.

Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1
In Example 1, the information recording medium 11 of FIG. 1 was manufactured, and the relationship between the material of the recording layer 406 and the erasing performance and signal reliability of the information layer 40 was examined. Specifically, eight types of information recording medium samples (1-1 to 1-8) including the recording layer 406 containing Sb and S and having different composition ratios of Sb and S are produced, and the information layer 40 The erasure performance and signal reliability were measured.

  The signal reliability is evaluated by the reproduction light deterioration. Here, reproduction light deterioration is defined as a decrease amount (dB) of signal intensity when a reproduction track (reproduction power Pr) is irradiated a predetermined number of times on a track on which a signal is recorded.

The sample was manufactured as follows. First, a polycarbonate substrate (diameter 120 mm, thickness 1.1 mm) on which a guide groove (depth 20 nm, track pitch 0.32 μm) for guiding the laser beam 31 was formed was prepared as the substrate 21. On the polycarbonate substrate, an Ag—Pd—Cu layer (thickness: 80 nm) as the reflective layer 402, and a (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layer (thickness: 25 nm) as the first dielectric layer 404. , Sb and S-containing recording layer 406 (thickness: 10 nm) (the composition ratio of Sb and S is as shown in Table 1), and the second interface layer (not shown) is (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ layers (thickness: 5 nm) and (ZnS) ₈₀ (SiO ₂ ) ₂₀ layers (thickness: 60 nm) were sequentially formed as the second dielectric layer 408 by sputtering.

The film forming apparatus for sputtering each of the above layers includes an Ag—Pd—Cu alloy sputtering target for forming the reflective layer 402 and (ZrO ₂ ) ₅₀ (In ₂ O for forming the first dielectric layer 404, respectively. ₃ ) ₅₀ sputtering target, sputtering target containing Sb and S for forming the recording layer 406, (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ sputtering target for forming the second interface layer, second The (ZnS) ₈₀ (SiO ₂ ) ₂₀ sputtering target for forming the dielectric layer 408 was provided. The shape of the sputtering target was 100 mm in diameter and 6 mm in thickness.

  The reflective layer 402 was formed in an Ar gas atmosphere with a pressure of 0.3 Pa, a DC power source, and an input power of 100 W. The first dielectric layer 404 was formed in an Ar gas atmosphere with a pressure of 0.1 Pa, an RF power source, and an input power of 200 W. The recording layer 406 was formed in an Ar gas atmosphere at a pressure of 0.2 Pa, using a DC power source and an input power of 50 W. The second interface layer was formed in an Ar gas atmosphere at a pressure of 0.1 Pa and using an RF power source with an input power of 200 W. The second dielectric layer 408 was formed in an Ar gas atmosphere with a pressure of 0.1 Pa and an RF power supply with an input power of 400 W.

  Finally, an ultraviolet curable resin (acrylic resin) is applied on the second dielectric layer 408 and rotated to form a uniform resin layer. A transparent layer 23 having a thickness of 100 μm was formed. Thereafter, an initialization process for crystallizing the recording layer 406 with a laser beam was performed. As described above, a plurality of samples having different materials for the recording layer 406 were manufactured.

  With respect to the sample thus obtained, the erasing performance and signal reliability of the information layer 40 of the information recording medium 11 were measured using the recording / reproducing apparatus of FIG. In the measurement, the wavelength of the laser beam 31 is 405 nm, the numerical aperture NA of the objective lens 32 is 0.85, and the linear velocity of the sample at the time of measurement is 19.7 m / s (corresponding to 4 × speed of the Blu-ray disc standard), The shortest mark length (2T) was 0.149 μm.

Table 1 shows the evaluation results of the composition of the recording layer 406, the erasing performance of the information layer 40, and the signal reliability for each sample. The erasing performance was evaluated by the value of the erasing rate. The evaluation criteria are as follows.
25dB or more “○”,
20 dB or more and less than 25 dB “△”,
Less than 20 dB “×”.

The signal reliability was evaluated by the amount of deterioration of the reproduction light after irradiation of reproduction light of Pr = 0.35 mW 1 million times. The evaluation criteria are as follows.
Less than 0.3 dB “○”,
0.3 dB or more and less than 2 dB “△”,
2 dB or more “x”.

  In the above evaluation, media evaluated as “◯” and “△” means that the media can withstand practical use with respect to the evaluation item, and media with an evaluation of “x” cannot withstand practical use with respect to the item. means.

  In addition, a comprehensive evaluation of the media was conducted. In the above evaluation items, at least one medium evaluated as “×” is evaluated as “×”, and in any one of the above evaluation items, a medium evaluated as “△” is evaluated as “○”. In the above evaluation items, all media evaluated as “◯” were evaluated as “「 ”.

As a result, it was found that in Sample 1-1 in which the recording layer 406 is composed of only Sb, the crystallization speed of the recording layer was too high and the signal reliability was poor. Further, it was found that in Sample 1-8 in which the composition of the recording layer 406 was Sb ₄₅ S ₅₅ , the amount of added S was too large, the crystallization rate was lowered, and the erasing performance was deteriorated.

The recording layer 406 contains Sb and S, and the composition of the recording layer 406 is expressed by the formula (1): Sb _x S _100-x (atomic%) (where x is 50 ≦ x ≦ 98). Samples 1-2 to 1-7 were found to exhibit good erasure performance and signal reliability. From the above results, it was found that when the composition of the recording layer 406 is expressed by the formula (1), the medium including the recording layer shows good characteristics. Further, if x is 60 to 80., record media have been found to exhibit an even better properties.

(Example 2)
In Example 2, the information recording medium 11 of FIG. 1 was produced in the same manner as in Example 1, and the relationship between the material of the recording layer 406 and the erasing performance and signal reliability of the information layer 40 was examined. Specifically, the recording layer 406 includes Sb, S, and M (M is at least one element of Sn, Bi, In, Ge, and Mn) and has a different composition ratio with Sb / S / M. 25 types of samples (2-1 to 2-25) of the information recording medium 11 having 406 were produced, and the erasing performance and signal reliability of the information layer 40 were measured.

  The sample manufacturing method is the same as the manufacturing method used in Example 1. However, the recording layer 406 includes Sb, S, and M (M is at least one element of Sn, Bi, In, Ge, and Mn). An alloy sputtering target is set to a pressure of 0.2 Pa in an Ar gas atmosphere. It was formed by sputtering using a DC power source with an input power of 50 W.

The samples thus obtained were measured for erasure performance and signal reliability in the same manner as in Example 1. Table 2 shows the evaluation results of the composition of the recording layer 406, the erasing performance of the information layer 40, and the signal reliability for each sample. The erasing performance was evaluated by the value of the erasing rate. The evaluation criteria are as follows.
25dB or more “○”,
20 dB or more and less than 25 dB “△”,
Less than 20 dB “×”.

The signal reliability was evaluated by the amount of deterioration of the reproduction light after irradiation of reproduction light of Pr = 0.35 mW 1 million times. The evaluation criteria are as follows.
Less than 0.3 dB “○”,
0.3 dB or more and less than 2 dB “△”,
2 dB or more “x”.

  In the above evaluation, media evaluated as “◯” and “△” means that the media can withstand practical use with respect to the evaluation item, and media with an evaluation of “x” cannot withstand practical use with respect to the item. means.

  In addition, a comprehensive evaluation of the media was conducted. In the above evaluation items, at least one medium evaluated as “×” is evaluated as “×”, and in any one of the above evaluation items, a medium evaluated as “△” is evaluated as “○”. In the above evaluation items, all media evaluated as “◯” were evaluated as “「 ”.

As a result, in the sample 2-6 in which the composition of the recording layer 406 is (Sb _0.98 S _0.02 ) ₆₅ Ge ₃₅ , the amount of Ge added is large, so that the crystallization speed is lowered and the erasing performance is deteriorated. I understood it. Further, in sample 2-12 in which the composition of the recording layer 406 is (Sb _0.98 S _0.02 ) ₆₅ Sn ₃₅ , the amount of Sn added is large, so that the crystallization speed is too high and the signal reliability is poor. all right. Further, in Sample 2-17 in which the composition of the recording layer 406 is (Sb _0.7 S _0.3 ) ₆₅ In ₃₅ , since the amount of In added is large, the crystallization speed is reduced, and a practical erasing performance is obtained. I found it impossible.

The recording layer 406 includes Sb, S, and M1 (M is at least one element selected from Ge, Sn, and In), and the composition of the recording layer 406 is expressed by the formula (2):
(Sb _z S _1-z ) _100-y M1 _y (atomic%) (2)
(The subscript z represents the ratio of each atom when the total number of Sb atoms and the number of S atoms is 1, satisfying 0.5 ≦ z ≦ 0.98, and the subscript y is atomic%. Represents the composition ratio shown and satisfies 0 <y ≦ 30)
Samples 2-1 to 2-5, 2-7 to 2-11, and 2-13 to 2-16 represented by the above were found to have good erasure performance and signal reliability. From the above results, it was found that the composition of the recording layer 406 containing Sb, S, and M1 is preferably represented by the formula (2). In particular, from samples 2-1 to 2-4, samples 2-7 to 2-10, and samples 2-13 to 2-15, in the above formula (2), y is better when 2 ≦ y ≦ 20 is satisfied. It was found that a good characteristic was obtained.

In the sample 2-21 in which the composition of the recording layer 406 is (Sb _0.7 S _0.3 ) ₇₀ Mn ₃₀ , since the amount of added Mn is large, the crystallization speed is lowered and a practical erasing performance cannot be obtained. I understood it. Further, it was found that the composition of the recording layer was too fast (signal reliability was poor. Further, in the sample 2-25 in which the composition of the recording layer 406 was (Sb _0.7 S _0.3 ) ₇₀ Bi ₃₀ , it was added. It was found that since the amount of Bi is large, the crystallization speed is too high and the signal reliability is poor.

The recording layer 406 contains Sb, S, and M2 (M2 is at least one element selected from Bi and Mn), and the composition of the recording layer 406 is represented by the formula (3):
(Sb _a S _1-a ) _100-b M2 _b (atomic%) (3)
(The subscript a represents the ratio of each atom when the number of Sb atoms and the number of S atoms are combined, and satisfies 0.5 ≦ a ≦ 0.98, and the subscript b is atomic%. Represents the composition ratio shown and satisfies 0 <b ≦ 20)
Samples 2-18 to 2-20 and 2-22 to 2-24 represented by the following formulas showed good erasing performance and signal reliability. From the above results, it was found that the composition of the recording layer 406 containing Sb, S, and M2 is preferably represented by the formula (2). Furthermore, from Samples 2-18 and 2-19, it was found that better characteristics can be obtained when b satisfies 2 ≦ b ≦ 10 in the above formula (3).

  Furthermore, a recording medium containing two kinds of elements as M1 (Samples 2-26 and 2-29) and a recording medium containing both M1 and M2 (Samples 2-27, 2-28, 2-30 and 2-31) Also showed good erase performance and signal reliability.

(Example 3)
In Example 3, the information recording medium 11 of FIG. 1 was manufactured, and the relationship between the thickness of the recording layer 406 and the erasing performance and signal reliability of the information layer 40 was examined. Specifically, six types of samples (3-1 to 3-6) of the information recording medium 11 including the information layer 40 having different thicknesses of the recording layer 406 are manufactured, and the erasing performance and signal reliability of the information layer 40 are prepared. Sex was measured.

The sample manufacturing method is the same as the manufacturing method used in Example 1 except for the thickness of the recording layer 406. The recording layer 406 was formed by sputtering a sputtering target containing Sb and S in an Ar gas atmosphere at a pressure of 0.2 Pa and a DC power source with an input power of 50 W. The composition of the recording layer was Sb ₆₀ S ₄₀ .

Table 3 shows the evaluation results of the thickness of the recording layer 406, the erasing performance of the information layer 40, and the signal reliability for each sample thus obtained. The evaluation method was the same as the method used in Example 1. The erasing performance was evaluated by the value of the erasing rate. The evaluation criteria are as follows.
25dB or more “○”,
20 dB or more and less than 25 dB “△”,
Less than 20 dB “×”.

The signal reliability was evaluated by the amount of deterioration of the reproduction light after irradiation of reproduction light of Pr = 0.35 mW 1 million times. The evaluation criteria are as follows.
Less than 0.3 dB “○”,
0.3 dB or more and less than 2 dB “△”,
2 dB or more “x”.

  In the above evaluation, media evaluated as “◯” and “△” means that the media can withstand practical use with respect to the evaluation item, and media with an evaluation of “x” cannot withstand practical use with respect to the item. means.

  In addition, a comprehensive evaluation of the media was conducted. In the above evaluation items, at least one medium evaluated as “×” is evaluated as “×”, and in any one of the above evaluation items, a medium evaluated as “△” is evaluated as “○”. In the above evaluation items, all media evaluated as “◯” were evaluated as “「 ”.

  As a result, Sample 3-6 in which the recording layer 406 had a thickness of 16 nm showed a low signal reliability because the recording layer 406 was too thick. It was found that when the thickness of the recording layer 406 is in the range of 7 to 15 nm, the medium exhibits good erasing performance and signal reliability. From the above results, it was found that the thickness of the recording layer 406 containing Sb and S is preferably 15 nm or less. Further, if the recording layer 406 has a thickness in the range of 9 nm to 13 nm, very good characteristics were obtained.

Example 4
In Example 4, the information recording medium 13 of FIG. 4 is manufactured, the thickness of the recording layer 426 included in the second information layer 42, the erasure rate of the second information layer 42, the signal reliability, and the first information layer 41. The relationship with the signal intensity was investigated. Specifically, samples 4-1 to 4-6 of the information recording medium 13 including the information layer 42 having different thicknesses of the recording layer 426 are manufactured, and the erasure rate, signal reliability, and The signal intensity of the first information layer 41 was measured. Here, the signal intensity was evaluated by the magnitude of CNR. The information recording medium 13 corresponds to N = 2 when the number of information layers is N (N is an integer of N ≧ 2), and has two information layers.

The sample was manufactured as follows. First, a polycarbonate substrate (diameter 120 mm, thickness 1.1 mm) on which a guide groove (depth 20 nm, track pitch 0.32 μm) for guiding the laser beam 31 was formed was prepared as the substrate 21. Then, on the polycarbonate substrate, an Ag—Pd—Cu layer (thickness: 80 nm) as the reflective layer 412, and a (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layer (thickness: as the first dielectric layer 414). 25 nm), Sb ₆₀ S ₄₀ (thickness: 10 nm) as the recording layer 416, (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ layer (thickness: 5 nm) as the second interface layer (not shown), As the second dielectric layer 418, (ZnS) ₈₀ (SiO ₂ ) ₂₀ layers (thickness: 60 nm) were sequentially laminated by sputtering.

The film forming apparatus for sputtering each of the above layers includes an Ag—Pd—Cu alloy sputtering target for forming the reflective layer 412 and (ZrO ₂ ) ₅₀ (In ₂ O for forming the first dielectric layer 414. ₃ ) ₅₀ sputtering target, sputtering target containing Sb and S for forming the recording layer 416 (the composition is adjusted so that a film having a composition of Sb ₆₀ S ₄₀ is formed), and the second interface layer is formed (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ sputtering target for forming, and (ZnS) ₈₀ (SiO ₂ ) ₂₀ sputtering target for forming the second dielectric layer 418 were provided. The shape of the sputtering target was 100 mm in diameter and 6 mm in thickness.

  The reflective layer 412 was formed in an Ar gas atmosphere with a pressure of 0.3 Pa, a DC power source, and an input power of 100 W. The first dielectric layer 414 was formed in an Ar gas atmosphere with a pressure of 0.1 Pa, an RF power source, and an input power of 200 W. The recording layer 416 was formed in an Ar gas atmosphere with a pressure of 0.2 Pa, a DC power source, and an input power of 50 W. The second interface layer was formed in an Ar gas atmosphere at a pressure of 0.1 Pa and using an RF power source with an input power of 200 W. The second dielectric layer 418 was formed in an Ar gas atmosphere at a pressure of 0.1 Pa and using an RF power source with an input power of 400 W.

  Next, an ultraviolet curable resin (acrylic resin) was applied onto the second dielectric layer 418 by a spin coating method to form a uniform resin layer. A substrate on which a guide groove (depth 20 nm, track pitch 0.32 μm) was formed was put on and adhered, and then the resin was cured, and after the resin was cured, the substrate was peeled off. As a result, a separation layer 22 having a thickness of 25 μm in which a guide groove for guiding the laser beam 31 was formed on the second information layer 42 side was obtained.

Next, on the separation layer 22, a TiO ₂ layer (thickness: 20 nm) as the transmittance adjusting layer 421, an Ag—Pd—Cu layer (thickness: 10 nm) as the reflective layer 422, and the first dielectric layer 424 (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layers (thickness: 15 nm), Sb ₇₀ S ₃₀ layer as the recording layer 426, (ZrO ₂ ) ₅₀ (Cr ₂ O as the second interface layer (not shown)) ₃ ) ₅₀ layers (thickness: 5 nm) and (ZnS) ₈₀ (SiO ₂ ) ₂₀ layers (thickness: 40 nm) as the second dielectric layer 428 were sequentially stacked by sputtering.

The film forming apparatus for sputtering each of the above layers includes a TiO ₂ sputtering target for forming the transmittance adjusting layer 421, an Ag—Pd—Cu alloy sputtering target for forming the reflective layer 422, and a first dielectric layer. (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ sputtering target for forming 424, sputtering target containing Sb and S for forming the recording layer 426 (a film having a composition of Sb ₇₀ S ₃₀ is formed. (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ sputtering target for forming the second interface layer and (ZnS) ₈₀ (for forming the second dielectric layer 428). SiO ₂ ) ₂₀ sputtering target was provided. The shape of the sputtering target was 100 mm in diameter and 6 mm in thickness.

  The transmittance adjustment layer 421 is formed in an atmosphere of mixed gas of Ar and oxygen (oxygen gas at a ratio of 3% by volume with respect to the whole) at a pressure of 0.3 Pa and using an RF power source with an input power of 400 W. I went there. The reflective layer 422 was formed in an Ar gas atmosphere with a pressure of 0.3 Pa, a DC power supply, and an input power of 100 W. The first dielectric layer 424 was formed in an Ar gas atmosphere with a pressure of 0.1 Pa, an RF power source, and an input power of 200 W. The recording layer 426 was formed in an Ar gas atmosphere with a pressure of 0.2 Pa, a DC power source, and an input power of 50 W. The second interface layer was formed in an Ar gas atmosphere at a pressure of 0.1 Pa and using an RF power source with an input power of 200 W. The second dielectric layer 428 was formed in an Ar gas atmosphere with a pressure of 0.1 Pa, an RF power source, and an input power of 400 W.

  Finally, an ultraviolet curable resin (acrylic resin) is applied onto the second dielectric layer 428 by spin coating to form a uniform resin layer, and then the resin is cured by irradiating with ultraviolet rays. Thus, a transparent layer 23 having a thickness of 75 μm was formed. Thereafter, the recording layer 416 and the recording layer 426 were irradiated with a laser beam, and an initialization process for crystallizing the recording layers 416 and 426 was performed. As described above, a plurality of samples having different recording layer 426 thicknesses were manufactured.

  For the sample thus obtained, the erasing performance of the information layer 42, the signal reliability, and the signal intensity of the first information layer 41 of the information recording medium 13 were measured using the recording / reproducing apparatus of FIG. In the measurement, the wavelength of the laser beam 31 was 405 nm, the numerical aperture NA of the objective lens 32 was 0.85, the linear velocity of the sample during the measurement was 19.7 m / s, and the shortest mark length (2T) was 0.149 μm. .

Table 4 shows the evaluation results of the thickness of the recording layer 426, the erasing performance of the second information layer 42, the signal reliability, and the signal intensity of the first information layer 41 for each sample. The erasing performance was evaluated by the value of the erasing rate. The evaluation criteria are as follows.
25dB or more “○”,
20 dB or more and less than 25 dB “△”,
Less than 20 dB “×”.

The signal reliability was evaluated based on the reproduction light deterioration amount after irradiation of reproduction light with Pr = 0.7 mW 1 million times. The evaluation criteria are as follows.
Less than 0.3 dB “○”,
0.3 dB or more and less than 2 dB “△”,
2 dB or more “x”.

Further, the signal strength of the first information layer 41 was evaluated by CNR. The evaluation criteria are as follows.
40 dB or more “O”,
34dB or more and less than 40dB "△",
34 dB or less “×”.

  In the above evaluation, media evaluated as “◯” and “△” means that the media can withstand practical use with respect to the evaluation item, and media with an evaluation of “x” cannot withstand practical use with respect to the item. means.

  In addition, a comprehensive evaluation of the media was conducted. In the above evaluation items, at least one medium evaluated as “×” is evaluated as “×”, and in any one of the above evaluation items, a medium evaluated as “△” is evaluated as “○”. In the above evaluation items, all media evaluated as “◯” were evaluated as “「 ”.

  As a result, when the thickness of the recording layer 426 is in the range of 4 nm to 9 nm, a medium in which the erasing performance of the second information layer 42, the signal reliability, and the signal strength of the first information layer 41 are all good can be obtained. It was. Further, if the thickness of the recording layer 426 is within the range of 5 nm to 8 nm, better characteristics were obtained.

(Example 5)
In Example 5, the information recording medium 14 of FIG. 5 was manufactured, and the thickness of the recording layer 446 included in the fourth information layer 44, the erasure rate of the fourth information layer 44, the signal reliability, and the third information layer 43 The relationship between the signal strength, the signal strength of the second information layer 42, and the signal strength of the first information layer 41 was examined. Specifically, samples of the six types of information recording media 14 (5-1 to 5-6) including the information layers 44 having different thicknesses of the recording layers 446 are manufactured, and the erasure rate of the fourth information layer 44, The signal reliability, the signal strength of the third information layer 43, the signal strength of the second information layer 42, and the signal strength of the first information layer 41 were measured. Here, the signal intensity was evaluated by CNR. The information recording medium 14 has four information layers in the case of N = 4 when the number of information layers is N (N is an integer of N ≧ 2).

The sample was manufactured as follows. First, a polycarbonate substrate (diameter 120 mm, thickness 1.1 mm) on which a guide groove (depth 20 nm, track pitch 0.32 μm) for guiding the laser beam 31 was formed was prepared as the substrate 21. Then, on the polycarbonate substrate, an Ag—Pd—Cu layer (thickness: 80 nm) as the reflective layer 412, and a (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layer (thickness: as the first dielectric layer 414). 25 nm), Sb ₆₀ S ₄₀ (thickness: 10 nm) as the recording layer 416, (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ layer (thickness: 5 nm) as the second interface layer (not shown), As the second dielectric layer 418, (ZnS) ₈₀ (SiO ₂ ) ₂₀ layers (thickness: 60 nm) were sequentially laminated by sputtering.

The film forming apparatus for sputtering each of the above layers includes an Ag—Pd—Cu alloy sputtering target for forming the reflective layer 412 and (ZrO ₂ ) ₅₀ (In ₂ O for forming the first dielectric layer 414. ₃ ) ₅₀ sputtering target, sputtering target containing Sb and S for forming the recording layer 416 (the composition is adjusted so that a film having a composition of Sb ₆₀ S ₄₀ is formed), and the second interface layer is formed A (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ sputtering target for forming the second dielectric layer 418 and a (ZnS) ₈₀ (SiO ₂ ) ₂₀ sputtering target for forming the second dielectric layer 418. The shape of the sputtering target was 100 mm in diameter and 6 mm in thickness.

  The reflective layer 412 was formed in an Ar gas atmosphere with a pressure of 0.3 Pa, a DC power supply, and an input power of 100 W. The first dielectric layer 414 was formed in an Ar gas atmosphere with a pressure of 0.1 Pa, an RF power source, and an input power of 200 W. The recording layer 416 was formed in an Ar gas atmosphere with a pressure of 0.2 Pa, a DC power source, and an input power of 50 W. The second interface layer was formed in an Ar gas atmosphere at a pressure of 0.1 Pa and using an RF power source with an input power of 200 W. The second dielectric layer 418 was formed in an Ar gas atmosphere at a pressure of 0.1 Pa and using an RF power source with an input power of 400 W.

  Next, an ultraviolet curable resin (acrylic resin) was applied onto the second dielectric layer 418 by a spin coating method to form a uniform resin layer. A substrate on which guide grooves (depth 20 nm, track pitch 0.32 μm) were formed was covered and adhered to the resin layer, and then the resin was cured. After the resin was cured, the substrate was peeled off. As a result, a separation layer 22 having a thickness of 10 μm in which a guide groove for guiding the laser beam 31 was formed on the second information layer 42 side was obtained.

Thereafter, on the separation layer 22, a TiO ₂ layer (thickness: 30 nm) as the transmittance adjustment layer 421, an Ag—Pd—Cu layer (thickness: 8 nm) as the reflection layer 422, and a second dielectric layer 424. (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layers (thickness: 10 nm), Sb ₈₀ S ₂₀ layer (thickness: 4 nm) as the recording layer 426, and (ZrO ₂ ) as the second interface layer (not shown) ) ₅₀ (Cr ₂ O ₃ ) ₅₀ layers (thickness: 5 nm) and (ZnS) ₈₀ (SiO ₂ ) ₂₀ layers (thickness: 40 nm) as the second dielectric layer 428 were sequentially stacked by sputtering.

The film forming apparatus for sputtering each of the above layers includes a TiO ₂ sputtering target for forming the transmittance adjusting layer 421, an Ag—Pd—Cu alloy sputtering target for forming the reflective layer 422, and a first dielectric layer. (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ sputtering target for forming 424, sputtering target containing Sb and S for forming the recording layer 426 (a film having a composition of Sb ₈₀ S ₂₀ is formed. (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ sputtering target for forming the second interface layer, and (ZnS) ₈₀ for forming the second dielectric layer 428. (SiO ₂ ) _{20 A} sputtering target is provided. The shape of the sputtering target was 100 mm in diameter and 6 mm in thickness.

  The transmittance adjustment layer 421 is formed in an atmosphere of mixed gas of Ar and oxygen (oxygen gas at a ratio of 3% by volume with respect to the whole) at a pressure of 0.3 Pa and using an RF power source with an input power of 400 W. I went there. The reflective layer 422 was formed in an Ar gas atmosphere with a pressure of 0.3 Pa, a DC power supply, and an input power of 100 W. The first dielectric layer 424 was formed in an Ar gas atmosphere with a pressure of 0.1 Pa, an RF power source, and an input power of 200 W. The recording layer 426 was formed in an Ar gas atmosphere at a pressure of 0.2 Pa, using a DC power source and an input power of 50 W. The second interface layer was formed in an Ar gas atmosphere at a pressure of 0.1 Pa and using an RF power source with an input power of 200 W. The second dielectric layer 428 was formed in an Ar gas atmosphere with a pressure of 0.1 Pa, an RF power supply, and an input power of 400 W.

  Next, an ultraviolet curable resin (acrylic resin) was applied onto the second dielectric layer 428 by a spin coating method to form a uniform resin layer. On this resin layer, a substrate on which guide grooves (depth 20 nm, track pitch 0.32 μm) were formed was covered and adhered, and then the resin was cured. After the resin was cured, the substrate was peeled off. As a result, a separation layer 28 having a thickness of 15 μm in which a guide groove for guiding the laser beam 31 was formed on the third information layer 43 side was obtained.

Next, on the separation layer 28, a TiO ₂ layer (thickness: 30 nm) as the transmittance adjustment layer 431, an Ag—Pd—Cu layer (thickness: 8 nm) as the reflection layer 432, and a second dielectric layer 434 are formed. (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layers (thickness: 10 nm), Sb ₈₀ S ₂₀ layer (thickness: 4 nm) as the recording layer 436, and (ZrO ₂ ) as the second interface layer (not shown) ) ₅₀ (Cr ₂ O ₃ ) ₅₀ layers (thickness: 5 nm) and (ZnS) ₈₀ (SiO ₂ ) ₂₀ layers (thickness: 38 nm) as the second dielectric layer 438 were sequentially laminated by sputtering.

The film forming apparatus for sputtering each of the above layers includes a TiO ₂ sputtering target for forming the transmittance adjusting layer 431, an Ag—Pd—Cu alloy sputtering target for forming the reflective layer 432, and a first dielectric layer. (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ sputtering target for forming 434, sputtering target containing Sb and S for forming the recording layer 436 (a film having a composition of Sb ₈₀ S ₂₀ is formed. (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ sputtering target for forming the second interface layer, and (ZnS) ₈₀ for forming the second dielectric layer 438. A (SiO ₂ ) ₂₀ sputtering target was provided. The shape of the sputtering target was 100 mm in diameter and 6 mm in thickness.

  The transmittance adjusting layer 431 is formed in an atmosphere of a mixed gas of Ar and oxygen (oxygen gas at a ratio of 3% by volume with respect to the whole) at a pressure of 0.3 Pa and using an RF power source with an input power of 400 W. I went there. The reflective layer 432 was formed in an Ar gas atmosphere with a pressure of 0.3 Pa, a DC power source, and an input power of 100 W. The first dielectric layer 434 was formed in an Ar gas atmosphere with a pressure of 0.1 Pa, an RF power source, and an input power of 200 W. The recording layer 436 was formed in an Ar gas atmosphere with a pressure of 0.2 Pa, a DC power source, and an input power of 50 W. The second interface layer was formed in an Ar gas atmosphere at a pressure of 0.1 Pa and using an RF power source with an input power of 200 W. The second dielectric layer 438 was formed in an Ar gas atmosphere with a pressure of 0.1 Pa, an RF power source, and an input power of 400 W.

  Next, an ultraviolet curable resin (acrylic resin) was applied onto the second dielectric layer 438 by a spin coating method to form a uniform resin layer. On this resin layer, a substrate on which guide grooves (depth 20 nm, track pitch 0.32 μm) were formed was covered and adhered, and then the resin was cured. After the resin was cured, the substrate was peeled off. As a result, a separation layer 29 having a thickness of 10 μm in which a guide groove for guiding the laser beam 31 was formed on the fourth information layer 44 side was obtained.

Thereafter, on the separation layer 29, a TiO ₂ layer (thickness: 25 nm) as the transmittance adjustment layer 441, an Ag—Pd—Cu layer (thickness: 7 nm) as the reflection layer 442, and a second dielectric layer 444 are formed. (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layers (thickness: 10 nm), (Sb _0.85 S _0.15 ) ₉₅ Ge ₅ layer as the recording layer 446, (ZrO ₂ ) as the second interface layer (not shown) ₅₀ (Cr ₂ O ₃ ) ₅₀ layers (thickness: 5 nm) and (ZnS) ₈₀ (SiO ₂ ) ₂₀ layers (thickness: 35 nm) as the second dielectric layer 448 were sequentially laminated by sputtering.

The film forming apparatus for sputtering each of the above layers includes a TiO ₂ sputtering target for forming the transmittance adjusting layer 441, an Ag—Pd—Cu alloy sputtering target for forming the reflective layer 442, and a first dielectric layer. (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ sputtering target for forming 444, sputtering target containing Sb, S and Ge for forming the recording layer 446 ((Sb _0.85 S _0.15 ) ₉₅ Ge ₅ composition (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ sputtering target and second dielectric layer 448 for forming the second interface layer are formed. (ZnS) ₈₀ (SiO ₂ ) ₂₀ sputtering target was provided. The shape of the sputtering target was 100 mm in diameter and 6 mm in thickness.

  The transmittance adjusting layer 441 is formed in an atmosphere of mixed gas of Ar and oxygen (oxygen gas at a ratio of 3% by volume with respect to the whole) at a pressure of 0.3 Pa and using an RF power source with an input power of 400 W. I went there. The reflective layer 442 was formed in an Ar gas atmosphere with a pressure of 0.3 Pa, a DC power source, and an input power of 100 W. The first dielectric layer 444 was formed in an Ar gas atmosphere at a pressure of 0.1 Pa, using an RF power source and an input power of 200 W. The recording layer 446 was formed in an Ar gas atmosphere with a pressure of 0.2 Pa, a DC power source, and an input power of 50 W. The second interface layer was formed in an Ar gas atmosphere at a pressure of 0.1 Pa and using an RF power source with an input power of 200 W. The second dielectric layer 448 was formed in an Ar gas atmosphere with a pressure of 0.1 Pa and an RF power supply with an input power of 400 W.

  Finally, an ultraviolet curable resin (acrylic resin) is applied onto the second dielectric layer 448 by spin coating to form a uniform resin layer, and then the resin is cured by irradiating with ultraviolet rays. Thus, a transparent layer 23 having a thickness of 65 μm was formed. After that, an initialization process for crystallizing the recording layer 416, the recording layer 426, the recording layer 436, and the recording layer 446 using a laser beam was performed. As described above, a plurality of samples having different recording layer 446 thicknesses were manufactured.

  For the sample thus obtained, the erasing performance of the information layer 42 of the information recording medium 13, the signal reliability, the signal strength of the third information layer 43, and the second information layer 42 using the recording / reproducing apparatus of FIG. And the signal strength of the first information layer 41 were measured. In the measurement, the wavelength of the laser beam 31 was 405 nm, the numerical aperture NA of the objective lens 32 was 0.85, the linear velocity of the sample during the measurement was 19.7 m / s, and the shortest mark length (2T) was 0.149 μm. .

For each sample, the thickness of the recording layer 446, the erasing performance and signal reliability of the second information layer 42, the signal strength of the third information layer 43, the signal strength of the second information layer 42, and the signal of the first information layer 41 The strength evaluation results are shown in (Table 5). The erasing performance was evaluated by the value of the erasing rate. The evaluation criteria are as follows.
25dB or more “○”,
20 dB or more and less than 25 dB “△”,
Less than 20 dB “×”.

The signal reliability was evaluated by the amount of deterioration of the reproduction light after the reproduction light of Pr = 1.4 mW was irradiated 1 million times. The evaluation criteria are as follows.
Less than 0.3 dB “○”,
0.3 dB or more and less than 2 dB “△”,
2 dB or more “x”.

The signal strength of each information layer was evaluated by CNR. The evaluation criteria are as follows.
40 dB or more “O”,
34dB or more and less than 40dB "△",
34 dB or less “×”.

  In the above evaluation, media evaluated as “◯” and “△” means that the media can withstand practical use with respect to the evaluation item, and media with an evaluation of “x” cannot withstand practical use with respect to the item. means.

  As a result, it was found that Sample 5-1 in which the thickness of the recording layer 446 was 1 nm was inferior in erasing performance because the recording layer 446 was too thin and the crystallization speed was reduced. If the thickness of the recording layer 446 is in the range of 2 to 6 nm, the erasing performance and signal reliability of the fourth information layer 44, the signal intensity of the third information layer 43, the signal intensity of the second information layer 42, It was also found that the signal strength of the first information layer 41 was good.

(Example 6)
In Example 6, the information recording medium 15 of FIG. 6 was produced, and the performance was evaluated in the same manner as in Examples 1 and 2. The sample was manufactured as follows. First, as the substrate 24, a polycarbonate substrate (diameter 120 mm, thickness 0.6 mm) on which guide grooves (depth 40 nm, track pitch 0.68 μm) for guiding the laser beam 31 were prepared. On the polycarbonate substrate, (ZnS) ₈₀ (SiO ₂ ) ₂₀ layer (thickness: 60 nm) as the second dielectric layer 408 and (ZrO ₂ ) ₅₀ (Cr ₂ ) as the second interface layer (not shown). O ₃ ) ₅₀ layers (thickness: 5 nm), a recording layer 406 (thickness: 10 nm) containing Sb and S, or Sb, S and M, and having different composition ratios, as a first dielectric layer 404 ( A ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layer (thickness: 25 nm) and an Ag—Pd—Cu layer (thickness: 80 nm) as the reflective layer 402 were sequentially laminated by a sputtering method. The film forming apparatus, sputtering target, film forming conditions (gas type, pressure, input power) and the like used are the same as those used in Example 1.

  After forming the information layer, an ultraviolet curable resin (acrylic resin) was applied onto the dummy substrate 26 by a spin coating method to form a uniform resin layer (thickness 20 μm). Next, the reflective layer 402 on the substrate 24 was brought into close contact with the dummy substrate 26, and then the ultraviolet ray was irradiated from the dummy substrate 26 side to cure the resin. As a result, the substrate 24 and the dummy substrate 26 were bonded via the adhesive layer 27. Finally, an initialization process for crystallizing the entire surface of the recording layer 406 with a laser beam was performed.

  For the samples thus obtained, the erasing performance and signal reliability of the information layer 40 of the information recording medium 15 were measured by the same method as in Examples 1 and 2. In the measurement, the wavelength of the laser beam 11 was 405 nm, the numerical aperture NA of the objective lens 41 was 0.65, the linear velocity of the sample during the measurement was 22.4 m / s, and the shortest mark length was 0.173 μm.

As a result, as in Example 1, the recording layer 406 contains Sb and S, and the composition of the recording layer 406 is expressed by the formula (1): Sb _x S _100-x (atomic%) (where x is The sample represented by 50 ≦ x ≦ 98) showed good erasing performance and signal reliability.

Similarly to Example 2, the recording layer 406 includes Sb, S, and M1 (M1 is at least one element selected from GeSn and In), and the composition of the recording layer 406 is represented by the formula (2 ): (Sb _z S _1-z ) _100-y M1 _y (atomic%) (The subscript z represents the ratio of each atom when the total number of Sb atoms and the number of S atoms is 1, and 0 .5 ≦ z ≦ 0.98, the subscript y represents a composition ratio expressed in atomic%, and 0 <y ≦ 30)), a sample represented by good erasing performance and signal reliability. Indicated.

Further, similarly to Example 2, the recording layer 406 includes Sb, S, and M2 (M1 is at least one element selected from Bi and Mn), and the composition of the recording layer 406 is represented by the formula (3). ): (Sb _a S _1-a ) _100-b M2 _b (atomic%) (The subscript a represents the ratio of each atom when the total number of Sb atoms and the number of S atoms is 1, and 0 .5 ≦ a ≦ 0.98, the subscript b represents the composition ratio expressed in atomic%, and 0 <b ≦ 20 is satisfied). Indicated.

(Example 7)
In Example 7, the information recording medium 15 of FIG. 6 was produced, and the performance was evaluated in the same manner as in Example 3.

The sample manufacturing method is the same as the manufacturing method used in Example 6 except for the thickness of the recording layer 406. The recording layer 406 was formed by sputtering a sputtering target containing Sb and S in an Ar gas atmosphere with a pressure of 0.2 Pa, a DC power supply, and an input power of 50 W. The composition of the recording layer 406 was Sb ₆₀ S ₄₀ .

  The samples thus obtained were evaluated for erasure performance and signal reliability in the same manner as in Example 1. As a result, as in Example 3, it was found that when the thickness of the recording layer 406 is in the range of 7 to 15 nm, both the erasing performance and the signal reliability are good.

(Example 8)
In Example 8, the information recording medium 17 of FIG. 8 was produced, and the performance was evaluated in the same manner as in Example 4.

The sample was manufactured as follows. First, as the substrate 24, a polycarbonate substrate (diameter 120 mm, thickness 0.6 mm) on which guide grooves (depth 40 nm, track pitch 0.68 μm) for guiding the laser beam 31 were prepared. On the polycarbonate substrate, a (ZnS) ₈₀ (SiO ₂ ) ₂₀ layer (thickness: 40 nm) is formed as the second dielectric layer 428, and (ZrO ₂ ) ₅₀ (as the second interface layer (not shown)). Cr ₂ O ₃ ) ₅₀ layers (thickness: 5 nm), Sb ₇₀ S ₃₀ layer as recording layer 426, (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layer (thickness: 15 nm) as first dielectric layer 424 ), An Ag—Pd—Cu layer (thickness: 10 nm) as the reflective layer 422, and a TiO ₂ layer (thickness: 20 nm) as the transmittance adjusting layer 421 were sequentially stacked by a sputtering method. The film forming apparatus, sputtering target, film forming conditions (gas type, pressure, input power), and the like used are the same as those used in forming the second information layer 42 in Example 4.

As the substrate 25, a polycarbonate substrate (diameter 120 mm, thickness 0.58 mm) on which a guide groove (depth 40 nm, track pitch 0.68 μm) for guiding the laser beam 31 was prepared. Then, on the polycarbonate substrate, an Ag—Pd—Cu layer (thickness: 80 nm) as the reflective layer 412, and a (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layer (thickness: as the first dielectric layer 414). 25 nm), Sb ₆₀ S ₄₀ (thickness: 10 nm) as the recording layer 416, (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ layer (thickness: 5 nm) as the second interface layer (not shown), As the second dielectric layer 418, (ZnS) ₈₀ (SiO ₂ ) ₂₀ layers (thickness: 60 nm) were sequentially laminated by a sputtering method. The film forming apparatus, sputtering target, film forming conditions (gas type, pressure, input power), and the like used are the same as those used in forming the first information layer 41 in Example 4.

  Thereafter, an ultraviolet curable resin (acrylic resin) was applied onto the second dielectric layer 418 on the substrate 25 by a spin coating method to form a uniform resin layer (thickness 20 μm). Next, the transmittance adjusting layer 421 on the substrate 24 was brought into close contact with the substrate 25, and then the resin was cured by irradiation with ultraviolet rays from the substrate 24 side. As a result, the substrate 24 and the substrate 25 were bonded via the adhesive layer 27. Finally, an initialization process for crystallizing the entire surface of the recording layer 416 and the recording layer 426 with a laser beam was performed.

  With respect to the sample obtained in this manner, the erasing performance, signal reliability, and signal strength of the first information layer of the information recording medium 17 were measured by the same method as that used in Example 4. It was measured. In the measurement, the wavelength of the laser beam 31 was 405 nm, the numerical aperture NA of the objective lens 41 was 0.65, the linear velocity of the sample during the measurement was 22.4 m / s, and the shortest mark length was 0.173 μm.

  As a result, as in Example 4, when the thickness of the recording layer 426 is in the range of 4 to 9 nm, the erasing performance and signal reliability of the second information layer 42 and the signal intensity of the first information layer 41 are It was found to be good.

Example 9
In Example 9, the information recording medium 18 of FIG. 9 was produced, and the performance was evaluated in the same manner as in Example 5.

The sample was manufactured as follows. First, as the substrate 24, a polycarbonate substrate (diameter 120 mm, thickness 0.6 mm) on which guide grooves (depth 40 nm, track pitch 0.68 μm) for guiding the laser beam 31 were prepared. On the polycarbonate substrate, (ZnS) ₈₀ (SiO ₂ ) ₂₀ layer (thickness: 35 nm) as the second dielectric layer 448 and (ZrO ₂ ) ₅₀ (Cr ₂ ) as the second interface layer (not shown). O ₃ ) ₅₀ layers (thickness: 5 nm), (Sb _0.85 S _0.15 ) ₉₅ Ge ₅ layer as recording layer 446, (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layer (thickness) as second dielectric layer 444 Thickness: 10 nm), an Ag—Pd—Cu layer (thickness: 7 nm) as the reflective layer 442, and a TiO ₂ layer (thickness: 25 nm) as the transmittance adjusting layer 441 were sequentially laminated by a sputtering method. The film forming apparatus, sputtering target, film forming conditions (gas type, pressure, input power), and the like used are the same as those used in forming the fourth information layer 44 of Example 5.

  Next, an ultraviolet curable resin (acrylic resin) was applied on the transmittance adjusting layer 441 by a spin coating method to form a uniform resin layer. On this resin layer, a substrate on which guide grooves (depth 40 nm, track pitch 0.68 μm) were formed was covered and adhered, and then the resin was cured. After the resin was cured, the substrate was peeled off. As a result, a separation layer 29 having a thickness of 15 μm in which a guide groove for guiding the laser beam 31 was formed on the third information layer 43 side was obtained.

Thereafter, a (ZnS) ₈₀ (SiO ₂ ) ₂₀ layer (thickness: 38 nm) as the second dielectric layer 438 and (ZrO ₂ ) ₅₀ as the second interface layer (not shown) are formed on the separation layer 29. (Cr ₂ O ₃ ) ₅₀ layers (thickness: 5 nm), Sb ₈₀ S ₂₀ layer (thickness: 4 nm) as the recording layer 436, and (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) as the second dielectric layer 434 ₅₀ layers (thickness: 10 nm), an Ag—Pd—Cu layer (thickness: 8 nm) as the reflective layer 432, and a TiO ₂ layer (thickness: 30 nm) as the transmittance adjusting layer 431 were sequentially stacked by sputtering. The film forming apparatus, sputtering target, film forming conditions (gas type, pressure, input power), and the like used are the same as those used in forming the third information layer 43 in Example 5.

  Next, an ultraviolet curable resin (acrylic resin) was applied on the transmittance adjusting layer 431 by a spin coating method to form a uniform resin layer. On this resin layer, a substrate on which guide grooves (depth 40 nm, track pitch 0.68 μm) were formed was covered and adhered, and then the resin was cured. After the resin was cured, the substrate was peeled off. As a result, a separation layer 28 having a thickness of 10 μm in which a guide groove for guiding the laser beam 31 was formed on the second information layer 42 side was obtained.

Thereafter, a (ZnS) ₈₀ (SiO ₂ ) ₂₀ layer (thickness: 40 nm) as the second dielectric layer 428 and (ZrO ₂ ) ₅₀ as the second interface layer (not shown) are formed on the separation layer 28. (Cr ₂ O ₃ ) ₅₀ layers (thickness: 5 nm), Sb ₈₀ S ₂₀ layer (thickness: 4 nm) as the recording layer 426, (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) as the second dielectric layer 424 ₅₀ layers (thickness: 10 nm), an Ag—Pd—Cu layer (thickness: 8 nm) as the reflective layer 422, and a TiO ₂ layer (thickness: 30 nm) as the transmittance adjusting layer 421 were sequentially stacked by sputtering. The film forming apparatus, sputtering target, film forming conditions (gas type, pressure, input power), and the like used are the same as those used in forming the second information layer 42 in Example 5.

As the substrate 25, a polycarbonate substrate (diameter 120 mm, thickness 0.56 mm) on which guide grooves (depth 40 nm, track pitch 0.68 μm) for guiding the laser beam 31 were prepared. Then, on the polycarbonate substrate, an Ag—Pd—Cu layer (thickness: 80 nm) as the reflective layer 412, and a (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layer (thickness: as the first dielectric layer 414). 25 nm), Sb ₆₀ S ₄₀ (thickness: 10 nm) as the recording layer 416, (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ layer (thickness: 5 nm) as the second interface layer (not shown), As the second dielectric layer 418, (ZnS) ₈₀ (SiO ₂ ) ₂₀ layers (thickness: 60 nm) were sequentially laminated by a sputtering method. The film forming apparatus, sputtering target, film forming conditions (gas type, pressure, input power) and the like used are the same as those used in forming the first information layer 41 in Example 5.

  Thereafter, an ultraviolet curable resin was applied onto the second dielectric layer 428 of the substrate 25 by a spin coating method to form a uniform resin layer (thickness: 15 μm). The transmittance adjusting layer 431 of the substrate 24 was brought into close contact with the resin layer, and then the resin was cured by irradiating ultraviolet rays from the substrate 24 side. Thereby, the substrate 24 and the substrate 25 were bonded via the adhesive layer 27. Finally, an initialization process for crystallizing the entire surface of the recording layers 416, 426, 436, and 446 with a laser beam was performed.

  For the sample obtained in this manner, the erasing performance and signal reliability of the fourth information layer 44 of the information recording medium 18, the signal intensity of the third information layer 43, by the same method as used in Example 5, The signal intensity of the second information layer 42 and the signal intensity of the first information layer 41 were measured. In the measurement, the wavelength of the laser beam 11 was 405 nm, the numerical aperture NA of the objective lens 41 was 0.65, the linear velocity of the sample during the measurement was 22.4 m / s, and the shortest mark length was 0.173 μm.

  As a result, as in Example 5, when the thickness of the recording layer 446 is in the range of 2 to 6 nm, the erasing performance and signal reliability of the fourth information layer 44, the signal intensity of the third information layer 43, the first It was found that the signal strength of the second information layer 42 and the signal strength of the first information layer 41 were good.

  From the results of Examples 3, 4, 5, 7, 8, and 9, it was found that in the information recording media 11 to 18, the thickness of the recording layer is preferably in the range of 2 nm to 15 nm. That is, when the recording layer containing Sb and S has a thickness in the range of 2 nm to 15 nm, good performance was ensured in the medium.

(Example 10)
A medium having the same configuration as that of the information recording medium manufactured in Example 4 was manufactured by changing the composition of the recording layer 426 included in the second information layer 42. The composition of the recording layer 426 was Sb ₇₀ Sn ₃₀ in the sample 10-1, and Sb ₇₀ Ge ₃₀ in the sample 10-2. In Samples 10-1 and 10-2, the recording layer was subjected to a pressure of 0.2 Pa in an Ar gas atmosphere using an SbSn alloy target (Sample 1 0-1 ) and an SbGe alloy target (Sample 1 0-2 ), respectively. Then, using a DC power source, the input power was 50 W. The material and formation conditions of the other layers were the same as those of the sample prepared in Example 4.

  Sample 4-5 produced in Example 4 was prepared for comparison with Samples 10-1 and 10-2. In order to measure the transmittance of the second information layer of these samples, the first information layer 41 and the separation layer 22 of the information recording medium 13 shown in FIG. A sample for transmittance measurement in which only the transparent layer 23 was formed was prepared, and the relationship between the recording layer composition of the recording layer 426 and the transmittance of the second information layer 42 was examined.

The transmittance measurement sample was manufactured as follows. First, a polycarbonate substrate (diameter 120 mm, thickness 1.1 mm) on which a guide groove (depth 20 nm, track pitch 0.32 μm) for guiding the laser beam 31 was formed was prepared as the substrate 21. On the substrate 21, a TiO ₂ layer (thickness: 20 nm) as the transmittance adjusting layer 421, an Ag—Pd—Cu layer (thickness: 10 nm) as the reflective layer 422, and a first dielectric layer 424 (ZrO _2). ) ₅₀ (In ₂ O ₃ ) ₅₀ layers (thickness: 15 nm), recording layer 426 (thickness: 8 nm), (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ as the second interface layer (not shown) A layer (thickness: 5 nm) and a second dielectric layer 428 (ZnS) ₈₀ (SiO ₂ ) ₂₀ layers (thickness: 40 nm) were sequentially laminated by a sputtering method. The formation conditions of each layer were the same as those of the sample produced in Example 4.

  Finally, an ultraviolet curable resin is applied onto the second dielectric layer 428 by a spin coating method to form a uniform resin layer, and then the resin is cured by irradiating with ultraviolet rays, thereby having a thickness of 75 μm. A transparent layer 23 was formed. Thereafter, an initialization process for crystallizing the recording layer 426 with a laser beam was performed. As described above, samples for transmittance measurement with different recording layer compositions of the recording layer 426 were manufactured.

  The transmittance at a wavelength of 405 nm of these transmittance measurement samples was measured with a spectrometer, and the measured value was defined as the transmittance of the second information layer. A sample having a transmittance of 49% or more was evaluated as “◯”, and a medium having a transmittance of less than 49% was evaluated as “x”. The evaluation results are shown in Table 6.

  In Sample 4-5 corresponding to the present invention, the transmittance of the second information layer was high, and therefore the signal intensity of the first information layer was sufficiently large. Samples 10-1 and 10-2 that did not contain S in the recording layer had a low transmittance, and thus the signal intensity of the first information layer was lower than that of sample 4-5.

(Example 11)
A medium having the same configuration as that of the information recording medium manufactured in Example 5 was manufactured by changing the composition of the recording layer 446 included in the fourth information layer 44. The composition of the recording layer 446 was Sb ₈₀ Sn ₂₀ in the sample 11-1, and Sb ₈₀ Ge ₂₀ in the sample 11-2. In Samples 11-1 and 11-2, the recording layer was made of SbSn alloy target (Sample 11-1) and SbGe alloy target (Sample 11-2), respectively, and the pressure was 0.2 Pa in an Ar gas atmosphere. Using a DC power source, the input power was 50 W. The material and formation conditions of the other layers were the same as those of the sample prepared in Example 5.

  In order to compare with these samples, Sample 5-5 prepared in Example 5 was prepared. In order to measure the transmittance of the fourth information layer of these samples, the first, second, and third information layers 41, 42, and 43 and the separation layers 22, 28, and 29 of the information recording medium 14 shown in FIG. A transmittance measurement sample in which only the fourth information layer 44 and the transparent layer 23 are formed on the substrate 21 is prepared, and the relationship between the recording layer composition of the recording layer 446 and the transmittance of the fourth information layer 44 is prepared. I investigated.

The transmittance measurement sample was manufactured as follows. First, a polycarbonate substrate (diameter 120 mm, thickness 1.1 mm) on which a guide groove (depth 20 nm, track pitch 0.32 μm) for guiding the laser beam 31 was formed was prepared as the substrate 21. The transmittance adjusting layer 441 is a TiO ₂ layer (thickness: 25 nm), the reflective layer 442 is an Ag—Pd—Cu layer (thickness: 7 nm), and the second dielectric layer 444 is (ZrO ₂ ) ₅₀ (In ₂ O ₃ ) ₅₀ layers (thickness: 10 nm), recording layer 446 (thickness: 5 nm), (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ layers (thickness: 5 nm) as the second interface layer (not shown) ), (ZnS) ₈₀ (SiO ₂ ) ₂₀ layers (thickness: 35 nm) were sequentially stacked as the second dielectric layer 448 by a sputtering method. The formation conditions of each layer were the same as those of the sample produced in Example 5.

  Finally, an ultraviolet curable resin is applied onto the second dielectric layer 448 by a spin coating method to form a uniform resin layer, and then the resin is cured by irradiating with ultraviolet rays, thereby having a thickness of 65 μm. A transparent layer 23 was formed. Thereafter, an initialization process for crystallizing the recording layer 446 with a laser beam was performed. As described above, samples for transmittance measurement with different recording layer compositions of the recording layer 446 were manufactured.

  The transmittance at a wavelength of 405 nm of these transmittance measurement samples was measured with a spectrometer, and the measured value was defined as the transmittance of the fourth information layer. A sample having a transmittance of 68% or more was evaluated as “◯”, and a medium having a transmittance of less than 68% was evaluated as “x”. Table 7 shows the evaluation results.

  In Sample 5-5 corresponding to the present invention, the transmittance of the fourth information layer was high, and thus the signal intensity of the first to third information layers was sufficiently large. Samples 11-1 and 11-2, which do not contain S in the recording layer, have a low transmittance, and thus the signal intensity of the first to third information layers was lower than that of sample 5-5.

(Example 12)
In Example 12, the electrical information recording medium 61 without the second recording layer 66 was manufactured in the electrical information recording medium 61 shown in FIG. 12, and the phase change due to the application of the current was confirmed.

A Si substrate having a nitrided surface was prepared as the substrate 62, and a layer made of Pt, having a surface area of 6 μm × 6 μm and a thickness of 0.1 μm was formed thereon as the lower electrode 63. On top of this, a layer made of (SiO ₂ ) ₅₀ (ZrO ₂ ) ₅₀ , having a surface area of 4.5 μm × 5 μm and a thickness of 0.01 μm was formed as the first dielectric layer 64. Further, as the first recording layer 65, a layer made of Sb ₈₀ S ₂₀ , having a surface area of 5 μm × 5 μm and a thickness of 0.05 μm was formed. As the second dielectric layer 67, a layer made of (SiO ₂ ) ₅₀ (ZrO ₂ ) ₅₀ , having a surface area of 4.5 μm × 5 μm and a thickness of 0.01 μm was formed. As the upper electrode 68, a layer made of Pt, having a surface area of 5 μm × 5 μm and a thickness of 0.1 μm was formed. All layers were formed by sputtering.

  The first dielectric layer 64 and the second dielectric layer 67 were insulators. Accordingly, in order to pass a current through the first recording layer 65, the first dielectric layer 64 and the second dielectric layer 67 are formed to have a smaller surface area than the first recording layer 65, and the lower electrode 63 and the upper electrode 68 are formed. Each of them was in partial contact with the first recording layer 65.

  Thereafter, an Au lead wire was bonded to the lower electrode 63 and the upper electrode 68, and the electrical information recording / reproducing device 74 was connected to the electrical information recording medium 61 via the application unit 69. With this electrical information recording / reproducing device 74, a pulse power source 73 is connected between the lower electrode 63 and the upper electrode 68 via a switch 71. Furthermore, a change in resistance value due to a phase change in the first recording layer 65 was detected by a resistance measuring instrument 70 connected via a switch 72 between the lower electrode 63 and the upper electrode 68.

When the first recording layer 65 is in an amorphous phase, the recording waveform 901 shown in FIG. 15 is applied between the lower electrode 63 and the upper electrode 68, and a current pulse of I _c1 = 5 mA and t _c1 = 50 ns is applied. The first recording layer 65 transitioned from the amorphous phase to the crystalline phase. When the first recording layer 65 is in the crystalline phase, the erase waveform 906 shown in FIG. 15 is applied between the lower electrode 63 and the upper electrode 68, and a current pulse of I _a1 = 10 mA and t _a1 = 10 ns is applied. The first recording layer 65 transitioned from the crystalline phase to the amorphous phase.

  Further, when the number of repeated rewrites of the electrical phase change information recording medium 61 was measured, the number of repeated rewrites of the medium having the first dielectric layer 64 and the second dielectric layer 67 was the first dielectric layer 64 and the second dielectric layer 64. It was more than 10 times that of the medium without the dielectric layer 67. This is because the first dielectric layer 64 and the second dielectric layer 67 suppress mass transfer from the lower electrode 63 and the upper electrode 68 to the first recording layer 65.

The first recording layer 48 is made of an Sb—S-based material other than Sb ₈₀ S _{20 or} an Sb—SM material (M is at least one element selected from Sn, Bi, In, Ge, and Mn). The same results were obtained even when formed.

  The information recording medium of the present invention has a property (non-volatile) that can retain recorded information for a long time, and is a high-density rewritable optical disk or the like (for example, Blu-ray Disc Rewriteable (BD-RE), DVD-RAM). , DVD-RW, DVD + RW, etc.) or electrical memory.

  DESCRIPTION OF SYMBOLS 11 ... Information recording medium, 12 ... Information recording medium, 13 ... Information recording medium, 14 ... Information recording medium, 15 ... Information recording medium, 16 ... Information recording medium, 17. Information recording medium, 18 ... Information recording medium, 21 ... Substrate, 22 ... Separation layer, 23 ... Transparent layer, 24 ... Substrate, 25 ... Substrate, 26 ... Dummy substrate, 27 ... adhesion layer, 28 ... separation layer, 29 ... separation layer, 31 ... laser beam, 32 ... objective lens, 40 ... information layer, 41 ... first 1 information layer, 42 ... 2nd information layer, 43 ... 3rd information layer, 44 ... 4th information layer, 48 ... N-1 information layer, 49 ... Nth information layer , 402 ... reflective layer, 403 ... reflective layer side interface layer, 404 ... first dielectric layer, 405 ... first interface layer, 406 ... recording layer, 407 ... Second interface layer, 408 ... second dielectric layer, 412 ... reflective layer, 414 ... first dielectric layer, 416 ... recording layer, 418 ... second Electrical layer, 421 ... Transmittance adjustment layer, 422 ... Reflective layer, 424 ... First dielectric layer, 426 ... Recording layer, 428 ... Second dielectric layer, 431 ... transmittance adjustment layer, 432 ... reflection layer, 434 ... first dielectric layer, 436 ... recording layer, 438 ... second dielectric layer, 441 ... transmittance Adjustment layer, 442 ... reflection layer, 444 ... first dielectric layer, 446 ... recording layer, 448 ... second dielectric layer, 491 ... transmittance adjustment layer, 492. Reflecting layer, 494 ... first dielectric layer, 496 ... recording layer, 498 ... second dielectric layer, 501 ... laser diode, 502 ... laser beam, 503. ..Half mirror, 504 ... Objective lens, 505 ... Motor, 506 ... Information recording medium, 507 ... Photo detector, 61, 81 ... Electrical information recording medium, 62 ... Substrate , 63 ... lower electrode, 64 ... first dielectric layer, 65 ... first Recording layer, 66 ... second recording layer, 67 ... second dielectric layer, 68 ... upper electrode, 69 ... application section, 70 ... resistance measuring instrument, 71, 72 ... Switch 73 ... Pulse power supply 74 ... Electric information recording / reproducing device 75 ... Word line 76 ... Bit line 77 ... Memory cell 78 ... Addressing circuit 79 ... Storage device, 80 ... External circuit, 901, 902, 903, 904, 905, 908, 909 ... Recording waveform, 906,907 ... Erasing waveform, 667 ... Vacuum container, 668. ..Exhaust port, 669 ... gas supply port, 670 ... anode, 671 ... substrate, 672 ... sputtering target, 673 ... cathode, 674 ... power source.

Claims (24)

An information recording medium including N (N is an integer of 2 or more) information layers, wherein the N information layers are separated from the laser incident side by an Nth information layer, an N−1th information layer, an N−th information layer. Two information layers: When the second information layer and the first information layer are used, at least one of the second to N-th information layers includes a recording layer capable of causing a phase change, and the recording layer includes Sb and S And the following formula (1):
Sb _x S _100-x (Atom%) (1)
(Subscript x represents a composition ratio expressed in atomic%, and satisfies 50 ≦ x ≦ 98)
An information recording medium having a thickness in the range of 2 nm to 9 nm.   The information recording medium according to claim 1, wherein x satisfies 50 ≦ x ≦ 80 in the formula.   The information recording medium according to claim 1, wherein in the recording layer, Sb atoms and S atoms occupy 90 atomic% or more of all atoms constituting the recording layer.   The information recording medium according to claim 1, wherein in the recording layer, Sb atoms and S atoms occupy 99 atomic% or more of all atoms constituting the recording layer. The recording layer further contains M1 (M1 is at least one element selected from Ge, In, and Sn), and the following formula (2):
(Sb _z S _1-z ) _100-y M1 _y (atomic%) (2)
(The subscript z represents the ratio of each atom when the total number of Sb atoms and the number of S atoms is 1, satisfying 0.5 ≦ z ≦ 0.98, and the subscript y is atomic%. Represents the composition ratio shown and satisfies 0 <y ≦ 30)
The information recording medium according to claim 1, represented by:   The information recording medium according to claim 5, wherein in the recording layer, Sb atoms, S atoms, and M1 atoms occupy 99 atomic% or more of all atoms constituting the recording layer. The recording layer further contains M2 (M2 is at least one element selected from Bi and Mn), and the following formula (3):
(Sb _a S _1-a ) _100-b M2 _b (atomic%) (3)
(The subscript a represents the ratio of each atom when the number of Sb atoms and the number of S atoms are combined, and satisfies 0.5 ≦ a ≦ 0.98, and the subscript b is atomic%. Represents the composition ratio shown and satisfies 0 <b ≦ 20)
The information recording medium of Claim 1 containing the material represented by these.   The information recording medium according to claim 7, wherein in the recording layer, Sb atoms, S atoms, and M 2 atoms occupy 99 atomic% or more of all atoms constituting the recording layer. The recording layer further contains M1 and M2 (M1 is at least one element selected from Ge, In and Sn, and M2 is at least one element selected from Bi and Mn), and the following formula (4 ):
(Sb _c S _1-c ) _100-de M1 _d M2 _e (atomic%) (4)
(The subscript c represents the ratio of each atom when the total number of Sb atoms and the number of S atoms is 1, satisfying 0.5 ≦ c ≦ 0.98, and the subscripts d and e are atoms % Represents the composition ratio and satisfies 0 <d <30, 0 <e ≦ 20, 0 <d + e ≦ 30)
The information recording medium of Claim 1 containing the material represented by these.   10. The information recording medium according to claim 9, wherein in the recording layer, Sb atoms, S atoms, M1 atoms, and M2 atoms occupy 99 atomic% or more of all atoms constituting the recording layer.   The information recording medium according to claim 1, wherein N is two.   The information recording medium according to claim 1, wherein N is four. The information recording medium according to claim 11 or 12 , wherein the Nth information layer includes a recording layer containing the Sb and S. The recording layer containing Sb and S is a layer that undergoes a phase change when irradiated with a laser beam, and the information layer containing the recording layer containing Sb and S is at least a second dielectric layer, Sb and recording layer comprising a S, the first dielectric layer, and a reflective layer, the information recording medium according to any one of claims 1 to 1 3 comprising from the laser beam incident side in this order. The recording layer containing Sb and S is a layer that undergoes a phase change when irradiated with a laser beam, and the information layer containing the recording layer containing Sb and S is at least a second dielectric layer, Sb and recording layer comprising a S, the first dielectric layer, reflective layer, and the transmittance adjusting layer, the information recording according to any one of claims 1 to 1 3 comprising from the laser beam incident side in this order Medium. An information recording medium including N (N is an integer of 2 or more) information layers, wherein the N information layers are separated from the laser incident side by an Nth information layer, an N−1th information layer, an N−th information layer. 2 information layers: When the second information layer and the first information layer are used, at least one of the second to Nth information layers includes a recording layer capable of causing a phase change, and the recording layer includes A method for manufacturing an information recording medium, which is a recording layer containing Sb and S,
An information layer forming step including a step of forming the recording layer by a sputtering method. In the recording layer forming step, a sputtering target containing Sb and S is used, and a film formed using the sputtering target is formed. The following formula (1):
Sb _x S _100-x (Atom%) (1)
(Subscript x represents a composition ratio expressed in atomic%, and satisfies 50 ≦ x ≦ 98)
And a method for producing an information recording medium having a thickness in the range of 2 nm to 9 nm. The sputtering target further contains M1 (M1 is at least one element selected from Ge, In and Sn), and a film formed using the sputtering target has the following formula (2):
(Sb _z S _1-z ) _100-y M1 _y (atomic%) (2)
(The subscript z represents the ratio of each atom when the total number of Sb atoms and the number of S atoms is 1, satisfying 0.5 ≦ z ≦ 0.98, and the subscript y is atomic%. Represents the composition ratio shown and satisfies 0 <y ≦ 30)
The manufacturing method of the information recording medium of Claim 16 containing the material represented by these. The sputtering target further contains M2 (M2 is at least one element selected from Bi and Mn), and a film formed using the sputtering target has the following formula (3):
(Sb _a S _1-a ) _100-b M2 _b (atomic%) (3)
(The subscript a represents the ratio of each atom when the number of Sb atoms and the number of S atoms are combined, and satisfies 0.5 ≦ a ≦ 0.98, and the subscript b is atomic%. Represents the composition ratio shown and satisfies 0 <b ≦ 20)
The manufacturing method of the information recording medium of Claim 16 containing the material represented by these. The sputtering target further includes M1 and M2 (M1 is at least one element selected from Ge, In, and Sn, and M2 is at least one element selected from Bi and Mn), and the sputtering target is used. The film to be formed has the following formula (4):
(Sb _c S _1-c ) _100-de M1 _d M2 _e (atomic%) (4)
(The subscript c represents the ratio of each atom when the total number of Sb atoms and the number of S atoms is 1, satisfying 0.5 ≦ c ≦ 0.98, and the subscripts d and e are atoms % Represents the composition ratio and satisfies 0 <d <30, 0 <e ≦ 20, 0 <d + e ≦ 30)
The manufacturing method of the information recording medium of Claim 16 containing the material represented by these. Method of manufacturing an information recording medium according to any one of the N is claim 1 6-19 2. Method of manufacturing an information recording medium according to any one of the N is claim 1 6-19 4. The information layer forming step including a recording layer forming step including Sb and S includes at least a reflective layer forming step, a first dielectric layer forming step, and a recording layer forming including Sb and S. The method for manufacturing an information recording medium according to any one of claims 16 to 21 , comprising performing the step and the step of forming the second dielectric layer in this order. The information layer forming step including a recording layer forming step including Sb and S includes at least a second dielectric layer forming step, a recording layer forming step including Sb and S, and a first dielectric layer. step of forming the material layer, and the step of forming the reflective layer comprises performing in this order, the method of manufacturing an information recording medium according to any one of claims 1 6-21. Further comprising the method of manufacturing an information recording medium according to claim 2 2 or 2 3 that the before or after the step of forming the reflective layer, a step forming the transmittance adjustment layer.

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